Updated: December 8, 2020 9:10:37 pm
The finding is one of several important new results presented in the informational materials, which span 53 pages of analysis of data from the agency and Pfizer.
The coronavirus vaccine manufactured by Pfizer and BioNTech provides strong protection against COVID-19 within about 10 days of the first dose, according to documents released Tuesday by the Food and Drug Administration ahead of a meeting of its vaccine advisory group.
The finding is one of several important new results presented in the informational materials, which span 53 pages of analysis of data from the agency and Pfizer. Last month, Pfizer and BioNTech announced that their two-dose vaccine had a 95% efficiency rate after two doses given three weeks apart. The new analyzes show that protection starts to work much earlier.
Also, the vaccine worked well regardless of the volunteer’s race, weight, or age. While the trial did not find any serious adverse events caused by the vaccine, many participants experienced pain, fever, and other side effects.
On Thursday, the FDA’s vaccine advisory panel will discuss these materials before a vote on whether to recommend authorization of the vaccine from Pfizer and BioNTech.
Pfizer and BioNTech began a large-scale clinical trial in July, recruiting 44,000 people in the United States, Brazil and Argentina. Half of the volunteers received the vaccine and the other half the placebo.
New cases of coronavirus declined rapidly in the group of vaccinated volunteers about 10 days after the first dose, according to a graph in the informational materials. In the placebo group, the cases continued to increase steadily.
The rapid impact of the vaccine could benefit not only the people who receive it, but also the country’s hospitals that are under stress, slowing the flow of new patients to intensive care units.
Despite the early protection provided by the first dose, it is unclear how long that protection alone would last, underscoring the importance of the second dose. Previous studies have found that the second dose of the Pfizer-BioNTech vaccine gives the immune system a significant long-term boost, an effect seen in many other vaccines.
Many experts have expressed concern that coronavirus vaccines may protect some people better than others. But the results of the informational materials do not indicate such a problem. The vaccine has a high efficacy rate in both men and women, as well as similar rates in white, black, and Latino people. It also worked well in obese people, who are at higher risk of getting sick from COVID-19.
Some vaccines for other diseases trigger a weak immune response in older adults. But Pfizer and BioNTech found that people 65 and older received as much protection from the coronavirus vaccine as younger people.
Even if the vaccine is cleared by the FDA, the trial will continue. In the information papers, the companies said they would encourage people to stay in the trial as long as possible, without knowing whether they received the vaccine or the placebo, so that researchers could continue to collect information on whether the vaccine was safe and effective.
The informational materials also provide a deeper insight into vaccine safety. In any large clinical trial, some people who receive vaccines experience health problems that have nothing to do with the vaccine itself. Comparing your symptom rates to those in the placebo group, as well as to the history rates in a population, may indicate symptoms that may actually be caused by a vaccine.
The FDA concluded that there were “no significant imbalances” in serious health complications, known as adverse events, between the two groups. The agency noted that four people in the vaccinated group experienced a form of facial paralysis called Bell’s palsy, with no cases in the placebo group. The difference between the two groups was not significant and the rate in the vaccinated group was not significantly higher than in the general population.
The new data revealed that many volunteers who received the vaccine felt ill in the hours after the second dose, suggesting that many people may have to request a day off from work or be prepared to rest until symptoms subside. Among those aged 16 to 55, more than half developed fatigue, while 59% reported headaches. Just over a third felt chills and 37% felt muscle pain. About half of those over 55 years old felt fatigued, a third developed a headache, and about a quarter felt chills, while 29% experienced muscle pain.
On Monday, Kristen Choi, a psychiatric nurse and health services researcher at the University of California, Los Angeles, published a first-person account of the symptoms she experienced as a participant in the Pfizer-BioNTech trial.
“Clinicians should be prepared to discuss with patients why they should trust the vaccine and that its adverse effects could look a lot like COVID-19,” Choi wrote in the journal JAMA Internal Medicine. She advised doctors to tell patients that these unpleasant symptoms were “a sign that the vaccine is working, despite the unfortunate similarities to the symptoms of the disease.”
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