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In November, three drug companies announced promising test results from trials of COVID-19 vaccines. But we still don’t have answers to a few key questions.
Pfizer said its vaccine was 95 percent successful in keeping people from getting the disease. Moderna’s results showed a 94.5 percent effective rate. AstraZeneca, working in collaboration with the University of Oxford, released a study showing that its vaccine is safe, producing similar immune results for different age levels. More recently they announced an effectiveness rate of 90 percent in preventing COVID-19 in one of the dosing regimens tested.
Here are five things we still need to know:
As reported by Kaiser Health News, Pfizer says 94 out of about 40,000 people in their trial became ill with COVID-19. This number covers people who got two shots between July and October, but it does not indicate how long protection from the vaccine will last or how often people might need boosters to keep immunity.
“It’s a reasonable bet, but still a gamble that protection for two or three months is similar to six months or a year,” Dr. Paul Offit, a member of the Food and Drug Administration panel that is likely to review the vaccine for approval in December, said in the article,. Normally, vaccines aren’t licensed until they show they can protect for a year or two.
Another component Pfizer did not share is the percentage of participants in its trial who were in groups most likely to be hospitalized by COVID-19 – including people 65 and older and those with diabetes or obesity. The Oxford-AstraZeneca vaccine study did provide results showing that immune responses among people age 56 and older was similar to those aged 18 to 55. However, we still don’t know how effective their vaccine is until they complete their phase-three trials.
The National Academy of Medicine and the CDC have urged that older people be among the first groups to receive vaccines. Offit noted in the Kaiser article that vaccines under development by Novavax and Sanofi may be better for the elderly as they contain immune-stimulating particles similar to the Shingrix vaccine, which highly effective in protecting older people against shingles disease.
The Pfizer vaccine must be kept supercooled, on dry ice around 100 degrees below zero, from the time it is produced until a few days before it is injected. If it is kept at a temperature too high, it would quickly self-destruct. Moderna’s vaccine must be stored between 36 and 46 degrees Fahrenheit. Pfizer has devised a plan to transport the vaccine by truck in specially designed cases. However, there are still unknowns such as whether cases can protect vaccines from deteriorating in the warm sun, or the risk that mishandling the shipment during transport could render vaccines ineffective.
The International Air Transport Association, a trade group based in Geneva, Switzerland, said in an article by Newsweek that about 25 percent of current vaccines are “degraded” when delivered due to incorrect shipping or improper handling..
All three drugmakers have announced early results from various vaccine trials, but there’s no way of knowing whether each one will be best for all age groups or only for a specific population. However, if the FDA approves them quickly, it could become harder for manufacturers of other vaccines to carry out their own studies. People may be less likely to participate in trials if they think an effective vaccine already exists. These additional studies are still crucial because many different vaccines will likely be necessary to meet the global demand for protection.
On the flip side, recent announcements could speed the process for other COVID-19 vaccines. For instance, studies of the people who still got sick while participating in Pfizer’s vaccine trial could help scientists learn if they produced lower levels of antibodies than vaccinated individuals who remained well. As KHN explains, these results would let scientists know if there is a “correlate of protection” for COVID-19 – a level of antibodies that can predict whether someone is protected from the disease. This knowledge would allow public health officials to determine whether other vaccines under production were effective without having to test them on tens of thousands of people.
Do you plan to take a COVID-19 vaccine as soon as it’s available? Share your thoughts with Voices for Affordable Health.