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June 21, 2021

Ask the Expert: COVID vaccine efficacy, FDA approval and how the virus affects animals

"Ask the Expert" articles provide information and insights from MSU scientists, researchers and scholars about national and global issues, complex research and general-interest subjects based on their areas of academic expertise and study. They may feature historical information, background, research findings, or offer tips.

Aron Sousa, interim dean of MSU’s College of Human Medicine, and Birgit Puschner, dean of MSU’s College of Veterinary Medicine, answer questions about COVID-19 and vaccines.

When will the vaccines be fully approved by the FDA and what does that require?

Sousa: The companies that make the current vaccines in the U.S. Pfizer, Moderna and Johnson & Johnson have all of the data needed to submit for final FDA approval, and they had to present that data, which pertains to effectiveness, safety, toxicology and more, to the FDA to get their Emergency Use Authorization. Preparing the submission for final approval of vaccines takes time, but we believe Pfizer will likely put in its submission in late June or July. The FDA has already seen all of the information, so it is possible it could move on the submission quickly, but I don’t think we can make many predictions about whether the final approval will be done before fall. 

What studies are underway in terms of vaccine efficacy and variants?

Aron Sousa, interim dean of MSU’s College of Human Medicine.

Sousa: Just about every week there is a new study published about how well the vaccines cover new variants. Some studies look at whether the antibodies vaccinated people produce attach to the variant virus in a laboratory setting. These studies get done quickly after a new variant is found, but these antibody studies are just a hint about how vaccines work in the community. The most important studies look to see whether vaccinated people get sick from the new variants in their communities, and these studies take more time. So far, the vaccines we use in the U.S. do well in the antibody laboratory studies and the community studies against the known virus variants.

What data exist regarding length of immunity and possible requirements for booster shots? 

Sousa: Vaccinated people are very well protected against the virus. Very few vaccinated people get sick from COVID-19 and even fewer get sick enough to have long-lasting effects from the virus. From the early studies of the vaccines from last year and the first people vaccinated under the Emergency Use Authorization, the vaccines hold up well. Based on studies of the long-lasting memory cells in vaccinated people, it is possible, but not yet proven, that we may not need vaccine boosters anytime soon. 

People who are immunosuppressed by medications or some diseases may not develop good immunity from the vaccines or from getting sick with the virus. Those people are not as well protected by the vaccines. There may eventually be special guidelines for immunosuppressed individuals, but we do not know enough yet to create those guidelines.

What are the recommendations for vaccination for those with preexisting medical conditions?

Sousa: People with preexisting conditions should get vaccinated since they are most at risk from COVID-19, including lung, vascular and neurological damage that never really gets completely better. There are some reports that people with preexisting conditions have a rougher time after their vaccination than people without preexisting conditions, but compared to getting COVID-19, your odds are much better being vaccinated

Some people have had clotting problems in the past, and those people should know that the Janssen (Johnson & Johnson) vaccine has been associated with a rare clotting disorder. There is currently no medical contraindication to any of the vaccines, other than allergy to the vaccine.

What exemptions exist for vaccination, whether medical, religious or others?

Sousa: The COVID-19 vaccines are not mandatory. There are medical and religious exemptions for other vaccines that are mandatory.

Can pregnant women be safely vaccinated?

Sousa: The limited data looks good for vaccination of pregnant people, and there is reason to believe that the children of mothers who deliver while sick with COVID-19 have more problems than those who did not have COVID-19. Also, pregnant people are more likely to get severe COVID-19 than people who are not pregnant, so it is recommended pregnant people get vaccinated.

When should individuals who have had COVID-19 get vaccinated?

Sousa: The general agreement is that people who have had COVID-19 should still get vaccinated. The vaccine may provide better immunity than having had COVID-19 itself. And there also are many people who were not tested but had COVID-19 without showing symptoms. These people should get vaccinated as well. You can be vaccinated after you recover from COVID-19 and have met the isolation criteria. There is no minimum time between recovering from COVID-19 and getting your vaccination. The exception is those who received monoclonal antibodies as part of their COVID-19 treatment. These individuals need to wait 90 days after their antibody treatment before getting vaccinated. Monoclonal antibodies are an infusion used to treat COVID-19. These antibodies are meant to help stop the virus and might prevent the body from responding to vaccines. A 90-day wait allows those monoclonal antibodies to be cleared from the body before a vaccination.

Birgit Puschner, dean of MSU’s College of Veterinary Medicine.

Can cats and dogs get COVID-19 and transfer it to humans?

Puschner: SARS-CoV-2 has been confirmed in cats, dogs and ferrets. Currently, there is no evidence that animals play a role in spreading SARS-CoV-2 to humans. Dogs appear to be less susceptible to infection than cats, and ferrets have only been diagnosed in a laboratory setting. Confirmed cases in pets are very rare and, fortunately, result in mild or no clinical signs of illness. While dogs can be infected with SARS-CoV-2, there is no evidence that infection causes disease or that they transmit the virus to humans or other animals. Cats and ferrets are able to transmit infection to animals that are housed in the same cage. 

Will the coronavirus vaccines available protect my pet from COVID-19?

Puschner: There are other coronaviruses that infect animals and there are vaccines available for some of them. Although these viruses are in the coronavirus family, each is a very different virus. Vaccinating animals or people with existing coronavirus vaccines is not expected to provide cross-protection, and they should not be used for this purpose. Consult with your veterinarian about vaccines for your pets, including those to protect against canine coronavirus infection.  

What is the risk of COVID-19 infection in horses, cattle, sheep, goats and pigs?

Puschner: There are no documented cases of SARS-CoV-2 infection in horses or livestock species, and there is no evidence to date that humans present a risk for passing COVID-19 to farm animals. However, there are many coronaviruses of veterinary importance, such as transmissible gastroenteritis virus and porcine respiratory coronavirus in swine, infectious bronchitis virus in poultry, and equine and bovine coronavirus. While these are generally very contagious diseases within a group of animals, they are not often transmitted between species.

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