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Your Questions Answered

I usually host 10 people for Thanksgiving, including my elderly parents and preschool granddaughter. Is it safe to do so this year?

11.16.2021: After nearly two years of isolation and lockdowns, many people are planning family gatherings this holiday season now that COVID-19 infections are declining due to the widespread adoption of vaccines.

Whether it is wise to hold a large gathering in your home and the range of safety precautions you should take, ultimately depends on several factors: who is on your guest list, whether your guests are vaccinated and your own comfort level in accepting a certain degree of risk.

For those who are hosting or attending holiday gatherings, the CDC offers a variety of tips to minimize the risk of COVID-19 transmission.

Even so, some experts are taking a more cautious route and avoiding indoor social gatherings all together this year. In a recent poll, 28 infectious disease experts were asked about their holiday plans. Twelve said they weren’t planning a multigenerational Thanksgiving meal because of the risks involved; 14 said they were.

If you want to make your own decision, here are some guidelines and tips that might help:

  1. Let your guests know in advance that in order to protect themselves and others, like your grandfather and granddaughter, the best thing they can do is get vaccinated. Limiting your event to vaccinated guests only significantly reduces risk.
  2. Anyone who has cold or flu symptoms should stay home.
  3. Ask guests to be tested for COVID a few days before your event or invest in rapid home tests that can be administered at your door.
  4. Good ventilation is key. Weather permitting, open windows to improve indoor air circulation or have part of your gathering outdoors. Placing a commercial air purifier in the dining area, kitchen and living room also helps.
  5. Everyone should bring a well-fitting mask and should wear it if they are unvaccinated or in the presence of individuals who have weakened immune systems or are susceptible to serious illness.
  6. Remind guests to keep a safe distance when possible and to avoid dense clustering in tights spaces.
  7. Ask guests to limit their exposure to others at social gatherings in the weeks or days ahead of your event.
  8. Keep your guest list small. Yes, we all miss our close family members, but we’re not out of the woods yet with COVID-19 and this is not the year to plan a mega-family gathering.
Now that the U.S. travel ban for international visitors has lifted, is there anything my relatives overseas need to know before they visit me?

The chances for families to reunite during the upcoming holidays got a tremendous boost on Nov. 8 when the U.S. lifted an 18-month ban on international visitors coming from 33 countries. Those countries include members of the European Union, China, Iran, South Africa, Brazil and India. But the clearance is not absolute, and travelers are advised to bring important COVID-19 documentation with them if they plan to visit the U.S.

Visitors who are traveling by air must show proof of full vaccination and a recent negative coronavirus test prior to entering the U.S. Individuals visiting the U.S. via the land border crossings between Canada and Mexico will need to show proof of vaccination, but do not need to have evidence of a recent COVID-19 test.

According to the new travel rules, people visiting the U.S. no longer need to quarantine but must show proof of a negative COVID-19 test that was taken within three days of their departure. Unvaccinated American travelers returning the U.S. must take the test with 24 hours of their departure.

Self-testing is also acceptable as long as the tests have been approved by the U.S. Food and Drug Administration and provide prompt results. Self-administered tests must be taken under digital supervision so that a telehealth professional verifies a person’s identity and ensures that the test is administered properly.

When it comes to traveling with children, unvaccinated children ages 2 to 17 can enter the U.S. if they are traveling with a vaccinated adult and have had a negative coronavirus test result within three days of their departure. If a child is traveling alone or with an unvaccinated adult, they will need to have a negative COVID test withing 24 hours of travel.

Only certain vaccines are acceptable for entry into the U.S. Vaccines cleared by U.S. regulators or for emergency use by the World Health Organization are acceptable. Those outside of that category, such as the Sputnik V developed in Russia and the CanSino vaccine from China, are not acceptable vaccines for U.S. entry.

It should also be noted that masks are still required on airplanes traveling to the U.S. and at all U.S. airports.

More information about requirements for international travel to and from the U.S. can be found on this CDC website.

Is it true there is now a pill for the treatment of COVID-19?

Drug manufacturers Pfizer and Merck are both testing experimental pills for the treatment of COVID-19. There is interest in the pills because they allow people to be treated for COVID-19 infection in the comfort of their own homes should they have symptoms of the virus.

While Pfizer’s initial clinical trial looks the most promising, there is no pill for the treatment of COVID-19 currently available in the United States. Vaccines remain the best weapon in the fight against COVID-19. The pill-based treatments are for individuals who are ill with COVID-19. Needless to say, it is best to not be infected with COVID-19 in the first place and that is where vaccines are most effective.

In terms of a potential COVID-19 pill, Pfizer recently announced that its experimental pill known as Paxlovid was 89% effective in reducing the risk of hospitalization or death in high-risk adult patients with COVID-19 during an initial clinical trial.

The results are so encouraging that Pfizer submitted a formal request to the U.S. Food and Drug Administration on Nov. 16, 2021 seeking an emergency use authorization for the pill. If such an authorization is granted – and when that might happen is unclear – the Paxolvid pill could help reduce the number of serious ill COVID-19 patients filling up beds in hospital intensive care units.

The positive results came when the pill was administered within 5 days of COVID-19 symptom onset, Pfizer said. A low dose of another antiviral drug known as ritonavir, is administered with the pill in order to helps Paxolvid retain its potency in the body longer. Paxolvid is a protease inhibitor that stops the COVID virus from multiplying in the body.

Merck’s experimental COVID-19 pill, known as molnupiravir, reduced the risk of hospitalization or death in at-risk adults by about 50%, according to initial clinical trial results released by the company. The pill was recently deemed “safe and effective” for use by people with mild to moderate cases of COVID-19 in the U.K. But no such approval has been granted in the U.S.

To date, the only antiviral approved by the FDA for the treatment of COVID-19 is remdesivir. But that treatment must be given intravenously, and it is not as convenient for patients as a pill. Patients can also be treated with monoclonal antibodies, but that treatment also involves infusion or injection and must be done under strict medical supervision.

Can you get a flu shot at the same time you get an initial COVID-19 vaccine dose or booster shot?
10.7.2021: Yes! You can get a COVID-19 vaccine, or a COVID-19 booster shot, and a flu vaccine at the same time. If you haven’t gotten your currently recommended doses of COVID-19 vaccine, get a COVID-19 vaccine as soon as you can and ideally get a flu vaccine by the end of October.
Will we eventually need annual COVID-19 shots, similar to the annual flu shot? Also, why isn’t there a booster shot formulated specifically for COVID-19’s highly transmissible Delta variant?

10.7.2021: Yale School of Public Health Dean Sten Vermund, a pediatrician and infectious disease epidemiologist, addressed these questions in a recent interview with Popular Science. The short answer, Vermund said, is it is too early to tell whether COVID-19 booster shots will be needed on a regular basis. Scientists are still gathering data on the durability of the immune response in people who have been inoculated with a COVID-19 vaccine.

“Do we need boosters once a year like the flu, or do we need them every 10 years like tetanus, or do we need them twice a lifetime like measles?” Vermund said in the interview. “These are the questions we don’t know the answers to.”

In regard to needing a special booster shot to prevent infection with COVID’s Delta variant, Vermund said existing vaccine formulations appear to be doing a good job fighting multiple variants of the virus. This happens because the COVID-19 vaccines all target a spike-shaped protein on the virus’s surface.

“All of these variants have the architecture of their spike protein preserved enough so that the vaccine-induced immune response is protective,” Vermund said. “So far, I’m cautiously optimistic that we’re not going to need a huge cocktail of vaccines.”

I have heard that some people are taking ivermectin to prevent COVID-19. What is ivermectin and is it safe?

9.10.2021: Ivermectin is a drug used to treat or prevent parasites in animals, such as livestock and horses. For humans, ivermectin tablets can be prescribed at very specific doses for the treatment of parasitic worms. There are also topical (on the skin) formulations of ivermectin that are used to treat head lice and skin conditions like rosacea. The U.S. Food and Drug Administration (FDA) adamantly states that ivermectin has not been authorized or approved for use in preventing or treating COVID-19. Taking large doses of ivermectin is dangerous and can result in overdose, death and serious health consequences. Ivermectin meant for animals that weigh hundreds of pounds is very different from the tablets prescribed for humans and can be toxic in humans.

Interest in using ivermectin for the prevention and treatment of COVID-19 surfaced, particularly in Latin America, after an early preprint of a scientific study reported that the medication is highly effective in reducing COVID-19 deaths. But that study, which was not subject to peer review, has since been withdrawn due to widespread concerns that some of the data was fabricated and highly flawed. Large randomized clinical trials of ivermectin remain ongoing but at the current time there is a lack of sufficient clinical data to support its use for the treatment or prevention of COVID-19.

Is it safe for me to travel by plane for work if I am vaccinated but my spouse is immunocompromised and I have young children at home who are not vaccinated?

9.10.2021: Vaccines are safe and highly effective in reducing your risk of getting COVID-19 and spreading it to others. But no vaccine is 100 percent effective. So called “breakthrough” infections can and do occur in vaccinated people. Vaccinated people who get infected with COVID-19 are less likely to be hospitalized or become seriously ill, but they can spread the virus to others.

Given these conditions and the current prevalence of the highly contagious Delta variant, you should be aware of the risks involved when considering whether to travel. Unvaccinated adults and those with compromised immune systems should strongly consider not traveling at this time. If you are vaccinated and must travel, the U.S. Centers for Disease Control and Prevention (CDC) recommends taking the following precautions:

  • Wear a mask over your nose and mouth in public (many forms of public transportation such as planes, trains and buses require passengers to wear masks.)
  • Avoid crowds and maintain 6 feet of distance from anyone who is not traveling with you.
  • Wash your hands often and use hand sanitizer containing at least 60% alcohol.

Check your destination in advance and adhere to all state and local requirements upon your arrival. The CDC offers websites that can help with this information for both domestic and international travel. You should also abide by all existing precautions regarding testing and quarantining if you have COVID-19 symptoms, suspect you may have COVID-19 and are waiting for test results, or have been exposed to someone infected with the virus.

Doctors from the Yale School of Medicine provide additional travel guidance in this report.

If I need a booster shot, does that mean the vaccines aren’t working?
10.7.2021: Getting a booster shot does not mean a vaccine isn’t working. Vaccines are providing outstanding protection against severe COVID-19 illness and hospitalization, but it appears the antibodies produced by the vaccines do start to dissipate over time. A booster shot does just that, it provides a boost to your body’s immune system so it can continue its robust fight against COVID-19 until the spread of the virus is brought under control.
Will I experience side effects if I get a booster shot?
If you get a booster shot, you may experience side effects similar to those experienced during the dual-dose initial phase of the Pfizer-BioNTech vaccine, including possible fatigue and soreness around the injection site. But those symptoms have been described as mild to moderate. As with the initial vaccines, more serious reactions can occur, but they are rare.
If the mRNA used in some COVID-19 vaccines tells cells how to make a coronavirus spike protein, how long does the cell keep making the spike protein once it receives the information? Is it one and done, or does the cell keep making spike proteins continuously?

8.11.2021: According to the CDC, the mRNA in COVID-19 vaccines delivers instructions to our cells to make “a harmless piece” of the spike protein that is found on the surface of the virus that causes COVID-19. This piece of spike protein is enough for our body’s immune system to recognize the virus as an invading germ and to be on alert for it. The vaccine activates our immune system, which then makes antibodies to repel future infection. After the protein piece is made, the cell breaks down the mRNA and gets rid of it. The great thing about vaccines is that they help people to be protected without having to risk getting serious ill with COVID-19 and building antibodies through natural infection.

None of the vaccines authorized for use in the United States contain any of the live virus that causes COVID-19 and the vaccines cannot give someone COVID-19. The mRNA used in COVID-19 vaccines does not enter the nucleus of cells where our DNA (genetic material) is stored and it does not affect or interfere with our DNA in any way. Contrary to claims circulating on social media, the mRNA delivered to cells in the vaccines does not constitute gene therapy, which by definition involves deliberate changes to a person’s DNA. The mRNA vaccines do not change or alter a person’s DNA.

I understand that if we're fully vaccinated but have an underlying medical condition, we should wear a mask in public. But can we remove the mask when we are visiting with a friend or a loved one who is also fully vaccinated or should we leave it on?
8.10.2021: Professor Marney White, PhD, MS ’09, of the Yale School of Public Health’s Department of Social and Behavioral Sciences and Track Director for Critical Topics in Public Health for the YSPH Online Executive MPH Program, responds:

Because the Delta variant is leading to a high number of breakthrough infections, and because even vaccinated people can transmit the virus, it is recommended that you continue to wear a mask.

As an immunocompromised person myself, I understand that these risk-benefit decisions can become very exhausting – especially as guidance continues to change. At one time, I did feel safe around others whom I knew were fully vaccinated. However, now that we know that fully vaccinated people can still transmit the virus, I have changed my approach. If possible, try to schedule outdoor visits with people who do not reside with you. If you must visit indoors, then it is recommended that you continue to wear a mask.
I’ve had COVID-19 and recovered, do I still need to get vaccinated?

10.7.2021: Yes! You should get vaccinated regardless of whether you already had COVID-19.

Here’s why: “Reinfection can reasonably happen in three months or less,” said Jeffrey Townsend, the Elihu Professor of Biostatistics at the Yale School of Public Health and the lead author of a recent study that found reinfection by the virus that causes COVID-19 is likely. “Therefore, those who have been naturally infected should get vaccinated. Previous infection alone can offer very little long-term protection against subsequent infections.” If you had a mild case of COVID-19, your body likely generated fewer virus-fighting antibodies than would be generated by a vaccine and you therefore could be at increased risk of reinfection. Another scientific study found that unvaccinated COVID-19 survivors are two times more likely than vaccinated people to get COVID-19 again. There is also evidence that survivors of COVID-19 who get vaccinated have a particularly robust immune response to fight off future infections. So do yourself a favor and get a shot!
Can current COVID-19 tests tell me whether I am infected with a virus variant like Delta? How do people know if they have “regular” COVID vs. one of the variants of the virus?

8.6.2021: Associate Professor of Epidemiology (Microbial Diseases) Nathan Grubaugh, PhD., an expert in genetic disease surveillance who has been studying and tracking COVID-19 variants, answers:

No, most tests will not be able to differentiate between Delta and other variants. All they tell you is if the test detects SARS-CoV-2, the underlying virus that causes COVID-19. Determining if an infection was caused by Delta requires whole genome sequencing, and currently those results can only be used for population-level surveillance, not individual diagnostics. This may change with future tests as they are reviewed by the FDA.

Additional information about the Delta variant from Yale Medicine.

I hear the COVID-19 vaccine can cause heart problems in some children and teens. As a parent with two children (ages 14 and 9), who have yet to be vaccinated, should I be concerned?

Yale School of Public Health Dean Sten H. Vermund, a pediatrician and infectious disease epidemiologist answers:

Fortunately, heart inflammation cases are rare with less than 13 cases per million doses administered in the United States. Death rates from COVID are 608,000 in a U.S. population of 320 million, or 1,875 per million persons. Death rates in vaccinated persons are so low that they are hard to measure right now, though we hope to have estimates in the future. Happily, the heart inflammations have not been serious and have been reversable both with and without medical intervention. The University of Minnesota has a useful article.

A prominent professional basketball player recently tested positive for COVID-19 even though she was fully vaccinated. They said it was a “breakthrough” case. What is a “breakthrough case” of COVID-19 and does this mean the vaccines don’t always work?

Yale School of Public Health Dean Sten H. Vermund, a pediatrician and infectious disease epidemiologist answers:

A lot of people think of vaccines like a bug-zapper that blocks the bug completely. But it’s really more like a bug trapper that has an insecticide built in. It lets the bug in but prevents the invading bug from harming you. With vaccines, you can still get the virus, but it doesn’t do you much harm since your immune system responds so quickly, having been prepared by the vaccine. So the beauty of the COVID-19 vaccines is that they prevent you from getting seriously ill, but some vaccinated people might still get the virus and much milder disease. This Washington Post article explains “breakthrough” infections in more detail.

My 63-year-old uncle is refusing to get vaccinated because he’s afraid he might get Guillain-Barré syndrome if he gets the shot. Is this true?

The U.S. Food and Drug Administration recently added a warning to Johnson & Johnson’s COVID-19 vaccine based on preliminary reports of a very small number of cases of Guillain-Barré syndrome in patients who received the shot. The cases were usually identified about two weeks after vaccination, and they occurred mostly in men age 50 and older. Guillain-Barré Syndrome is a neurological condition in which the body’s immune system damages nerve cells, causing muscle weakness and sometimes paralysis.

But the number of people identified with the rare neurological disorder in connection with the J&J vaccine is extremely small - only 100 people out of 12.8 million doses given. The FDA has described the chances of getting Guillain-Barré from the J&J vaccine as “very low.” Your uncle also has other options for being vaccinated if he is concerned. No data has been presented to date linking either the Pfizer-BioNTech vaccine or the Moderna vaccine to any Guillain-Barré symptom side effects. Both of those vaccines use different technology than the J&J vaccine.

I have had COVID-19 and have received the two-shot Pfizer vaccine (no reactions). Can I get this new strain of COVID in Missouri?

If you’re referring to the COVID-19 Delta variant, which health officials suspect is driving a surge of new COVID-19 cases in Missouri, then the answer to your question is that you are probably safe given your current vaccine status. Scientists are still studying how different vaccines protect against the highly infectious Delta variant, but early indications are that the vaccines available in the U.S. – including the Pfizer-BioNTech vaccine – are protective against the Delta variant once a person is fully vaccinated (two weeks after second dose for the Pfizer vaccine). A recent study by Public Health England found that the Pfizer vaccine was 88% effective against symptomatic disease from the Delta variant. The Moderna vaccine is also reported to offer protection against the Delta variant, according a recent announcement by the company. On July 1, 2021, the Johnson & Johnson company reported that its vaccine was effective against the Delta variant. Missouri is one of several states federal health officials are watching closely due to the high number of individuals who remain unvaccinated there. In some Missouri counties, less than 30 percent of the population is fully vaccinated. The surge in new COVID-19 cases potentially driven by the highly contagious Delta variant underscores the importance of getting vaccinated to protect personal health and the health of others in your community.

There are many of us who cannot take or do not want to take the COVID-19 vaccine. Are there therapeutics available to treat people who become infected with COVID-19?

According to the Centers for Disease Control and Prevention (CDC), “The spectrum of medical therapies to treat coronavirus disease 2019 (COVID-19) is growing and evolving rapidly, including both drugs approved by U.S. Food and Drug Administration (FDA) and drugs made available under FDA emergency use authorization (EUA).” The National Institutes of Health (NIH) has updated information on these approved therapeutics as well as treatment guidelines for clinicians. For those choosing not to receive a COVID-19 vaccine, the CDC strongly recommends continuing to wear masks, practicing physical distancing, and good hygiene, including thorough hand washing.

Note: On June 17, 2021, the Biden administration announced it was investing $3 billion for the development of pills to fight the coronavirus. If all goes well in clinical trials, some of the most promising pills could be available by the end of the year, according to the New York Times.

I am 72 years old and experienced mild symptoms of COVID-19 last year. On several occasions since then, I have experienced audio hallucinations and on one occasion a visual hallucination. Could this be related to COVID-19?
If you are experiencing a specific health problem that is concerning to you, it is important you contact your health care provider right away. Some people who have had COVID-19 continue to experience symptoms months after their initial diagnosis. These so-called “COVID long-haulers” have reported symptoms such as brain fog, dizziness, fatigue and headaches. The best thing to do is to contact your health care provider. This article from the American Medical Association explains more. If you are experiencing any of the COVID-19 emergency warning signs – trouble breathing, persistent pain or pressure in your chest, new confusion, inability to wake or stay awake, and pale, gray, or blue-colored skin, lips or nail beds (depending on skin tone), the Centers for Disease Control and Prevention (CDC) recommends that you seek emergency medical care right away.
I hear that there is a microchip in the COVID-19 vaccine that can be used as a tracking device once it is delivered into my body. Is this true?
There are absolutely no microchips in the COVID-19 vaccines. This rumor is believed to have started due to a misunderstanding about state electronic vaccine records. These digital records are kept by individual physicians on computer rather than on paper as part of the routine modernization of recordkeeping. Electronic patient medical records also allow health care providers to share information about a patient more easily when they are undergoing specialized treatment or in an emergency. But there are no electronic components in the COVID-19 vaccines or in any vaccines.
Could you please define vaccine efficacy according to vaccine protocols?
There are multiple outcomes in each trial, typically some variation of these: COVID-19 infection and COVID-19 severe disease. Vaccine efficacy is calculated by comparing the incidence (proportion of persons within the time period who reach the defined endpoints of infection or disease) in the vaccine group with the incidence in the unvaccinated group. An example can help: a 95% vaccine efficacy means that instead of 10,000 COVID-19 cases in an unvaccinated population of 1 million (assuming 1% would get COVID-19 and 99% would not get it), there would be 500 cases (99.95% of the vaccinated population would be disease-free compared to 99% of the unvaccinated population).
How long is a typical long-term study for these vaccines?
These vaccinees will be studied for years, I think. But the “post-marketing surveillance” demanded for new products by the FDA brings in safety data and will also assess how fast (or whether) immune responses wane with time. This can be done in many more persons that those who were in the clinical trials.
The COVID-19 vaccines were made at “warp speed.” Have they been around long enough to really know if they are safe?
The COVID-19 vaccines approved for use have been extensively tested. Those tests have been independently verified by hundreds of scientists. Due to the public health emergency created by COVID-19, scientists around the world joined together in sharing critical information that resulted in the new vaccines being developed at unprecedented speed. But no steps were bypassed or overlooked. These vaccines went through the same rigorous review required of any new vaccine.
Will the vaccine give me COVID-19?
Pfizer/BioNTech’s and Moderna’s mRNA vaccines do not contain live SARS-CoV-2 coronavirus, so they cannot infect you with COVID-19. The Johnson & Johnson vaccine uses a modified adenovirus to carry the genetic code your body needs to fight COVID-19. Adenoviruses are mostly known to cause mild cold-like symptoms, but scientists altered the adenovirus used in the vaccine so that it won’t cause any disease.
Will the vaccine change my DNA?
The messenger RNA used in the Pfizer and Moderna vaccines does enter your cells, but it stops there. It doesn’t enter the nucleus of your cells that contain all of your DNA. And just like in Mission: Impossible, the mRNA is destroyed by the cell after it receives its instructions.