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Pfizer’s COVID vaccine demonstrates efficacy in clinical trials. Now what?

Last Monday, Pfizer announced preliminary findings from Phase III of clinical trials demonstrate that its SARS-CoV2 vaccine is effective in producing antibodies against COVID. Pfizer partnered with German biotech firm, BioNTech, to produce the vaccine. Pfizer is one of the two forerunners in Phase III of clinical trials to prove efficacy of an mRNA vaccine. The other being Moderna. mRNA vaccines are developed from re-engineered messenger RNA (mRNA), the molecules that relay genetic instructions from DNA to the cell’s protein-making machinery. The company’s technology sends synthetic mRNA into cells, which would hypothetically invoke an immune response that causes the body to develop antibodies against the virus. More information about mRNA technology is explained in our article about SHA’s Fireside Chat with Moderna senior leadership earlier this month.

Initial results exhibit that Pfizer and BioNTech’s vaccine, BNT162b2, produced a protective immune response in subjects with no serious adverse effects. This first interim efficacy analysis was conducted on Nov. 8, 2020 by an external, independent Data Monitoring Committee (DMC). The trial currently has more than 40,000 subjects enrolled in different countries. 90% efficacy, in this instance, means out of the 94 known COVID cases in subjects, more than 90% were subjects who had received the placebo drug, and not the mRNA vaccine. If this efficacy rate continues, it would make the vaccine more effective than the flu vaccine. The trial will continue until there are 164 cases of COVID among participants. 

The process for FDA approval of a vaccine has been truncated under Operation Warp Speed, and there are currently eleven vaccines in Phase III clinical trials. 90% efficacy is an astounding result and, if this remains the case, would lead to FDA emergency use authorization after two months of follow-up data established safety in subjects who received the vaccine. This data will be available at the end of November. The FDA had originally said this summer it would grant emergency use authorization to a vaccine that demonstrated greater than 50% efficacy.

The Pfizer vaccine is administered in two parts in a prime-boost vaccine strategy. The first dose, the priming dose, presents the coronavirus genetic coding to the body, which causes B-lymphocytes of the immune system to produce antibodies against the virus. The second dose of Pfizer’s vaccine, a booster vaccine, is given three weeks after the first dose and increases the number of these antibodies. Interestingly, in comparison to Moderna’s vaccine, Pfizer’s mRNA vaccine will need to be stored in glacial temperatures of -80 degrees Celsius. Moderna predicts its mRNA vaccine will only need to be stored at -20 degrees Celsius, which is a typical freezer temperature.

It is important to note that the vaccine is still in Phase III of clinical trials and these are not final results. The trial’s protocol allows for interim analyses to be performed by external experts to assess for safety and efficacy. The information about efficacy was announced in a news release by Pfizer, not from a peer-reviewed medical journal. Therefore, the data will need to be reviewed by medical experts before it can be confirmed. In addition, more time will need to pass to ensure long-term effects. The next step is that Pfizer will submit data from Phase III for scientific peer-reviewed publication. As the study continues, the final vaccine efficacy percentage may vary. The DMC has not reported any serious safety concerns and recommends that the study continue to collect additional safety and efficacy data as planned. Participants will continue to be monitored for two years to ensure the vaccine is effective and safe.

Pfizer’s current projections are that it will produce up to 50 million vaccine doses in 2020 and up to 1.3 billion doses in 2021, worldwide. Under Operation Warp Speed, the government stated this summer it would give Pfizer nearly $2B for 100 million vaccines to be distributed in the U.S. However, Pfizer did not take any federal money for R&D. If approved for emergency use authorization, healthcare workers and vulnerable populations will likely be the first to receive this vaccine. This could occur as early as January with more availability for the general public in the spring. Pfizer does not have the capacity to vaccinate the majority of the population, so it is important that other biotech companies produce positive results in their clinical trials. 

For the past week, the average number of new COVID cases has been more than 140,000 per day in the U.S. We are currently at over 240,000 COVID-related deaths and hospitals are hitting record levels nationwide. This is coming at a time when people are developing “COVID fatigue.” The mortality rate related to COVID is declining due to better medical and pharmacologic management, but hospitals have also not been functioning at overcapacity. Low mortality rates correlate with hospitals having enough beds, supplies and medical personnel to care for patients, a reality that may disappear in some parts of the country as infections continue to rise. 

It is important that we continue to mitigate risks of spread of infection. We have promising vaccine data and a new governing administration coming into office in January, but wide scale access to a vaccine remains months away at best. In the meantime, it is up to us to continue to practice social distancing and make smart decisions this winter.

Photo credit: https://www.pbs.org/newshour/health/pfizer-says-covid-19-vaccine-is-looking-90-percent-effective

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