Vaccines have transformed the world, saving hundreds of millions of lives. They are also, by far, our best hope for stopping the Covid-19 pandemic. Other options to stop the disease are to stay out of the way, which makes it difficult for our economy and our society, or to build “herd immunity” through a natural infection, which would kill more than a million people in the United States. and 10 million or more deaths worldwide. But the push for a vaccine against Covid-19 faces three key hurdles.
First, will it work? Preliminary studies indicate that several types of vaccines currently in development produce an immense immune response. This is good news, but it does not mean that the vaccine protects people from infection or disease. We do not know if the immune response is protective and, if so, to what extent this protection will have. (Protection ranges from 0% to 60% for flu vaccines to 95% or higher for some other vaccines.) Even if a vaccine protects against the disease, it may not prevent people become infected and spread the virus to others.
We also do not know whether all people will be protected by a new vaccine, particularly the elderly, who have a remarkably higher risk of Covid-19 and may be less likely to have a strong immune response. We also don’t know how long any protection will last. We don’t even know the natural protection from Covid-19 infection; for many vaccines, the extension of immunity to natural infection is the limit of its potential effectiveness.
We don’t know if everyone will be protected by a new vaccine.
However, we have ample reason to be optimistic that some vaccines will provide some level of protection and that it will be demonstrated before the end of 2020. Some vaccine candidates may be in doubt, and others the effectiveness may be reduced by a few. months. “Something that, of course, will take many months to know.” Different vaccines may be more or less effective, and some vaccines may work less well for some groups. And most vaccines fail to get approved; many of today’s promising candidates may fail. We just don’t know. That’s what studies are for.
Second, will it be safe? What can go wrong with new vaccines? A lot. Several vaccine candidates use a harmless virus as a “vector” to deliver the antigen. This technology is promising, but we have limited experience in using it. And we have never used DNA or RNA vaccines — the technology used for various developing Covid-19 vaccines — in humans.
We now know that a small proportion of children who contract Covid-19 have a life-threatening inflammatory disease, as their immune system reacts to the coronavirus. A vaccine can rarely create a similar immune storm that causes serious illness, particularly in children, either from the vaccine itself or from subsequent exposure to the virus. There is no particular reason to believe that Covid-19 vaccines cause this type of overreaction, but it is a risk and should be studied, both before and after approval.
Polio vaccination provides a prudent account. Shortly after the invention of the vaccine, a manufacturer contaminated a vaccine and many children were paralyzed. In 1976, when an outbreak of H1N1 flu in Fort Dix, NJ, aroused concern over a pandemic, President Gerald Ford led the effort to vaccinate tens of millions of Americans. But the dreaded pandemic never materialized, and the vaccine paralyzed more than 500 people, some of whom had problems for life.
Despite these rare and unfortunate episodes, vaccines are still surprisingly safe: thousands of doses are given to people around the world with few problems. However, the adverse events of vaccination may not be evident until hundreds of thousands or millions of people have been vaccinated, so there can be no safety shortcuts. Humility is in order.
Third, can we reach people? Although we can develop an effective vaccine with a reassuring safety record, will we be able to reach people? Making a vaccine is not easy. Errors or contamination can occur, even with experienced pharmaceutical companies, and not all companies that make new vaccines have experience.
And even if an effective, seemingly safe vaccine is produced in large quantities, it will be difficult to distribute it quickly and equitably, store it and send it to the right temperature, educate doctors and inform communities, and control uptake and possible harmful subsequent repercussions. . The protection that even a highly effective vaccine provides is only as good as our delivery systems. The measles vaccine is more than 90% effective, but the World Health Organization reports that more than 140,000 children died of the disease worldwide last year, most in communities with low vaccination rates.
Particularly in this election season, the vaccine evaluation process must be scientifically rigorous and open.
The biggest challenge in getting a vaccine against Covid-19 to people’s sufficient weapons will not be scientific, technical or logistical; will come for lack of confidence. Particularly in this election season, the vaccine evaluation process must be scientifically rigorous and open. Public confidence can be eroded by the large profit margins for vaccine manufacturers, the lack of transparency about the cost of production, and prices that do not take into account the fact that many vaccines benefit substantially from publicly funded research. Open meetings of key advisory committees of the Food and Drug Administration and disease control and prevention centers will be essential.
The level needs to be positioned with the American public in a way that has not been done during this pandemic. We don’t have enough evidence, so we have to prioritize. We do not have enough protective equipment for health workers, so we should produce reusable masks with N95 safety. And when the vaccines arrive, we won’t have enough for everyone. Different vaccines may be available at different times, and some probably work better than others. Governments will need to set priorities between different groups, taking into account factors such as the risk of serious Covid-19 disease, the protection of essential functions and equity. Workers in prisons, nursing homes, and hospitals, for example, and black and Hispanic men are more likely to be exposed to the virus and have underlying health conditions that make them especially vulnerable.
Also, vaccines do not provide perfect protection and will probably not end up completing the pandemic. In our interconnected world, a truly global vaccination campaign will be essential to America’s long-term economic and health recovery.
Even in the United States, unless the vaccine is extraordinarily effective and accepted, cases and clusters will continue, needing a rapid and effective public health response. Our society will still have to adapt to limit the spread of the virus, reducing close contact inside, holding hands, wearing masks and improving ventilation. And unless the vaccine is surprisingly potent or we discover very effective treatments, my 91-year-old mother will not return to her beloved choral practices.
Deploying a vaccine against Covid-19 is the most important thing we can do to restore some order and normalcy to our world. We cannot afford to be wrong.
—Dr. Frieden was the director of the CDC from 2009 to 2017. He is the president and CEO of Resolve to Save Lives (an initiative of the public health organization Vital Strategies) and a senior member of the Foreign Relations Council.
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