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Are these coronavirus vaccines safe? An expert weighs in


During four decades of work on coronaviruses, Linda Saif — a faculty member in Ohio State’s Food Animal Health Research Program within the College of Food, Agricultural and Environmental Sciences (CFAES) — has been involved in many of the veterinary coronavirus vaccines for animals.

The COVID-19 vaccines that received Emergency Use Authorization in December are the first to be approved for use in humans, even though seven coronaviruses have been identified in humans throughout history.

A member of Ohio State’s Infectious Diseases Institute (IDI), Saif recently discussed COVID-19 vaccine development during an IDI Symposium in early December. Following the discussion, Saif provided more answers to questions for Insights.

Are these vaccines safe?

Based on the available data accumulated in the animal studies and then the phase I-III human clinical trials, the current vaccines appear to be safe and effective. The safety and effectiveness vaccine data have been carefully reviewed by both the Food and Drug Administration scientists and an FDA vaccine advisory committee of highly qualified physicians and scientists.

The advisory committee  review proceedings were open to the public and can be accessed on the FDA website. Such reviews are rigorous and science-based, so they should instill confidence that in spite of the name Warp Speed, the vaccines are being evaluated based on safety and scientific merit.

There may be a warning based on recent data from the BioNtech/Pfizer vaccine that it be administered to anyone with severe allergies in a setting allowing for monitoring and rapid treatment of any severe allergic reaction if needed. Concerns about such possible allergic reactions are also often included for other vaccines as well, such as certain influenza vaccines (egg allergies).

Some populations have not been involved in the clinical trials, correct? What could that mean for those people?

This is true for children and pregnant women who were not included in the clinical trials. For both the BioNtech/Pfizer and Moderna vaccines, more limited numbers of older individuals as well as adolescents were included in the clinical trials.

Based on the available data, both vaccines will be given to the elderly, with more data forthcoming as vaccines are used in this group. BioNtech/Pfizer was approved for adolescents over 16, and Moderna was approved for only those over 18 based on the volunteers they enrolled in this category.

As for pregnant women who were excluded in the trails, they would need to consult with their doctors about whether to take the vaccines and if the benefits might outweigh the potential risks. Additional data will be needed to confirm safety and effectiveness in pregnant women.

Before this vaccine could be given to children there will need to be clinical trials in this age group. Also most vaccines are tested for safety in adults first before being tested in children, and there is a decreasing age scale used for the initial testing of children.

Will those vaccinated still need to wear masks?

Yes, for several reasons.

First, although the vaccines have been tested for their ability to prevent COVID-19, it is unclear if they prevent infection, especially of the upper respiratory tract, which could lead to nasal shedding and possibly asymptomatic transmission of virus to others. If this is the case, then it could be possible that vaccinated individuals still might transmit the virus to others.

However in such cases the amount of virus shed is likely reduced, so hopefully it may not be enough for effective virus transmission, especially if accompanied by universal mask wearing. Also, we still do not know how long either natural or vaccine-induced immunity will last, which is an important issue to maintain a critical level of immunity in the population to prevent reinfection.

Second, because the vaccine is not 100% effective and not all individuals will elect to receive the vaccine or are unable to receive it (pregnant women, infants, immunocompromised, etc.), and not all the population will be vaccinated at once, many people will remain susceptible and capable of transmitting the virus.

Due to limited vaccine availability, it is estimated it will take months to vaccinate even those high-risk groups eligible to receive the vaccines.

It is estimated that around 50% to 70% of the population (about 165 to 230 million in the United States) need to acquire immunity induced by the vaccine (or natural infection) for the pandemic to be finally controlled. This estimated level of herd immunity is also important because this means that if enough people get vaccinated so that herd immunity is induced, this will also protect those in the population who are unable to be vaccinated due to health/age status, etc.

Therefore, continued use of masks, handwashing and social distancing remain essential, even as vaccines are being used. It is up to the public and each individual to accept and get both doses of the vaccines and maintain these public health mitigation measures if we are finally to succeed in ending the pandemic.

Are these vaccines reason for optimism?

The vaccines are a great cause for optimism because they chart the way out of the pandemic by more rapidly inducing immunity and preventing disease and deaths in the population.

However, unless they can be scaled up and provided at low cost worldwide, it is likely that pockets of susceptibility would remain that could fuel the continued global outbreak. This is why international collaboration and cooperation such as through COVAX, WHO and initiatives through the Bill and Melinda Gates Foundation and others in bringing vaccines to all countries is critical to stem the pandemic worldwide.

It is also important to remember that when there are clusters of resistance to vaccine use among unvaccinated people, the virus can continue to circulate in these groups and then re-emerge in the general population as immunity wanes. The recent measles outbreaks that started in unvaccinated populations and then spread outside these groups are good examples.