Vaccines have changed the world and saved hundreds of millions of lives. They are also by far our best hope of stopping the Covid-19 pandemic. Our other options for stopping the disease are moving away from each other, disrupting our economy and society, or building “herd immunity” through a natural infection, which would mean more from one million deaths in the United States and 10 million or more deaths worldwide. But the push for a vaccine against Covid-19 faces three major hurdles.
First, will it work? Preliminary studies indicate that various types of developing vaccines produce a strong immune response. This is good news, but it does not mean that the vaccine protects people from infection or disease. We do not know whether the immune response is protective, and if so, how extensive that protection is. (Protection ranges from 0% to 60% for flu vaccines up to 95% or higher for some other vaccines.) Even if a vaccine protects against disease, it can prevent people from infecting and spreading the virus to others. .
Nor do we know whether all people are protected by a new vaccine ̵1; particularly older people, who are at a markedly higher risk than Covid-19 and may be less likely to have a strong immune response. We do not know how long any protection will last. We still don’t know how protective the natural infection is from Covid-19; for many vaccines, the immunity limit for natural infection is the maximum limit of their potential efficacy.
We don’t know if all people are protected by a new vaccine.
Still, we have ample reason to be optimistic that some vaccines will provide some level of protection, and that this will be demonstrated before the end of 2020. Some vaccine candidates may be duds, and others may be less effective in just a few months — something that, of course, takes many months to know. Different vaccines may be more or less effective, and some vaccines may work less well for some groups. And many vaccines never make it to approval; many of today’s promising candidates may fail. We just don’t know. That’s why studies.
Second, will it be safe? What could go wrong with new vaccines? Many. Several candidate vaccines use a harmless virus as a “vector” to deliver the antigen. This technology is promising, but we have limited experience using it. And we have never used DNA or RNA vaccines – the technology used for various Covid-19 vaccines in development – in humans.
We now know that a small proportion of children who contract Covid-19 get a potentially life-threatening inflammatory condition as their immune system reacts to the coronavirus. A vaccine can, in rare cases, 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 vaccines provide a history of caution. Shortly after the vaccine was invented, one manufacturer contaminated a lot, and many children were paralyzed. In 1976, when the H1N1 flu outbreak in Fort Dix, NJ, raised concerns about a pandemic, President Gerald Ford led the effort to vaccinate tens of millions of Americans. But the fear of a pandemic has never materialized, and the vaccine has paralyzed more than 500 people, some of whom have had lifelong problems.
Despite these rare and unfortunate episodes, vaccines are still very safe: millions of doses are given to people around the world, with few problems. However, adverse events from the vaccine may not be seen 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 bring it to people? Even if we can develop an effective vaccine with a reassuring initial safety record, will we be able to reach people? Manufacturing vaccines is not simple. Deficiencies 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, to store and send it at the right temperature, to educate doctors and inform communities and monitor the absorption and possible harmful effects. . The protection provided even by a highly effective vaccine is 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 from the disease worldwide last year – many in communities with low vaccination rates.
Particularly in this election season, the vaccine assessment process must be scientifically rigorous and open.
The biggest challenge for the Covid-19 vaccine to get enough people into arms will not be scientific, technical or logistical; it will come from a lack of trust. Particularly in this election season, the vaccine assessment process must be scientifically rigorous and open. Public confidence could be eroded by large profit margins for vaccine makers, a lack of transparency about the cost of production and prices that fail to take into account the fact that many vaccines benefit substantially. from publicly funded research. Open meetings of the main advisory committees of the Food and Drug Administration and the Centers for Disease Control and Prevention will be indispensable.
We need to reach out to the American public in a way that was not done during this pandemic. We don’t have enough tests, so we need to give priority. We do not have enough protective equipment for health care workers, so we have to produce masks that can be reused safely95. And when the vaccines arrive, we won’t have enough for everyone. Different vaccines may become available at different times, and some probably work better than others. Governments will have to set priorities among different groups, taking into account factors such as the risk of serious Covid-19 disease, the protection of essential functions and justice. Workers in prisons, nursing homes and hospitals, for example, and Black and Hispanic people are more likely to be exposed to the virus and have underlying health conditions that make them particularly vulnerable.
In addition, vaccines do not provide perfect protection and probably will not completely end the pandemic. In our interconnected world, a truly global vaccination campaign must be essential to America’s economic recovery and long-term health.
Even in the United States, as long as the vaccine is extraordinarily effective and accepted, cases and clusters continue, requiring rapid and effective public health responses. Our society will still have to adapt to limiting the spread of the virus – reducing close contact on the inside, keeping handshake, wearing masks and improving ventilation. And until the vaccine is surprisingly potent or we discover very effective treatments, my 91-year-old mother won’t be back to her beloved choir practices anytime soon.
Using a Covid-19 vaccine is the most important thing we can do to restore a certain order and normalcy in our world. We can’t afford to get it 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 fellow on the Foreign Relations Council.
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