New CDC data on the efficacy of Pfizer and Moderna COVID-19 vaccines

Researchers in the United States have conducted a study showing the actual efficacy of Pfizer-BioNTech and Moderna coronavirus disease 2019 (COVID-19) vaccines in the prevention of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. It was conducted.

Importantly, Mark Thompson and his colleagues on the CDC COVID-19 response team have also shown that the vaccine is very effective in reducing infections. Viral loadThe duration of illness of an individual who develops a sudden infection despite being vaccinated, with fever symptoms.

In a large prospective study of about 4,000 people, complete vaccination (two vaccinations) was 91% effective in preventing SARS-CoV-2 infection, and partial vaccination (one vaccination). Inoculation) was found to be 81% effective.

Among infected individuals, partially or fully vaccinated individuals have lower levels of viral RNA, lower risk of developing fever, and shorter duration of illness than unvaccinated individuals. became.

Researchers have found that the vaccines are only very effective in preventing infections if the data further confirm that these vaccines reduce viral load and, as a result, reduce the infectivity of SARS-CoV-2. Not the effects of breakthrough infections.

This has important implications for important front-line workers, given the potential for spreading the virus through frequent close contact with patients, colleagues and the general public, Thompson and colleagues said. say.

The preprinted version of the research treatise is medRxiv* While the server, article is being peer reviewed.

Potentially important secondary benefits of mRNA-based COVID-19 vaccine

Messenger RNA (mRNA) -based vaccines developed by Pfizer-BioNTech (BNT162b2) and Moderna (mRNA-1273) have been shown to be highly effective in preventing symptomatic COVID-19 in Phase III clinical trials. It has been.

Thompson et al. Recently reported an interim estimate of efficacy showing similar benefits after administration of an mRNA-based vaccine under real-world conditions.

However, “little is known about the potentially important secondary benefits of the mRNA COVID-19 vaccine, such as disease severity, viral RNA loading, and shorter viral RNA detection periods,” the team said. I will.

What did the researchers do?

Currently, Thompson and colleagues have completed weekly SARS-CoV-2 tests through December 14, eight healthcare professionals, first responders, and other important frontline employees in the United States. We analyzed a positive cohort of 3,975 people^Th, 2020, April 10^Th, 2021.

Researcher estimated Efficacy of Partial and complete vaccination to prevent SARS-CoV-2 infection, and the viral RNA loading of vaccinated individuals with breakthrough infections was compared to the viral RNA loading of unvaccinated infected individuals. did. The team also compared the frequency of fever symptoms and the duration of COVID-19 between the vaccinated and unvaccinated groups.

Participants collected their own nasal swabs in the central turbinate once a week, with or without symptoms such as COVID-19. Individuals who developed a disease such as COVID-19 also collected nasal swabs and saliva samples at the onset of symptoms.

Samples were tested for SARS-CoV-2 infection using qualitative and quantitative reverse transcription-polymerase chain reaction (RT-PCR). Vaccine efficacy was estimated for complete vaccination (12 days or longer on the second dose) and partial vaccination (14 days or longer on the first dose, up to 13 days on the second dose). ..

Vaccinated individuals received either Pfizer-Bio NTech’s BNT162b2 vaccine or Moderna’s mRNA-1273 vaccine, and efficacy was calculated by adjusting location, occupation, and regional viral circulation. ..

What did the study find?

The number of participants with SARS-CoV-2 infection confirmed by RT-PCR was 204 (5.1%), 16 of whom were partially or completely vaccinated and 156 were unvaccinated. It was.

The vaccination status of 32 patients was uncertain (less than 14 days after the first dose) and was therefore excluded from the study.

The estimated efficacy of vaccination in protection from SARS-CoV-2 infection was 91% for complete vaccination and 81% for partial vaccination.

Among infected participants, the average viral RNA load detected (Log10 copy / mL) was 2.3 in partially or fully vaccinated participants compared to 3.8 in unvaccinated participants. was.

Adjusted analysis showed a 40.2% lower viral RNA load after at least partial vaccination.

At least 25% of partially vaccinated individuals reported illnesses such as febrile COVID-19, compared to 63.1% of unvaccinated individuals.

This indicates that the relative risk of symptoms such as febrile COVID19 was reduced by 58%, at least after partial vaccination.

Vaccinated participants reported 6.4 days less ill than unvaccinated participants.

What is the meaning of research?

The researchers state that the estimates of vaccine efficacy in the actual environment reported here are consistent with the results of clinical trials.

They also state that the combination of virological and clinical effects is consistent with previous reports of reduced amount and duration of viral RNA detection after mRNA-based vaccination, and mitigation of COVID-19. I have.

“If additional data confirm that mRNA vaccination reduces the number of viral RNA particles and the detection period, which reduces the infectivity of SARS-CoV-2, then the mRNA vaccine is associated with SARS-CoV-2 infection. Not only is it very effective in preventing it, but it can also mitigate the effects of breakthrough infections, “says the team.

“This is especially important for important frontline workers, as they can infect the virus through frequent close contact with patients, colleagues and the general public,” concludes Thompson and colleagues.

*Important Notices

medRxiv Is published as a preliminary scientific report that has not been peer-reviewed and is therefore considered definitive, guides clinical practice / health-related behaviors, and is treated as established information. It’s not a thing.