Pfizer, Moderna vaccines highly effective after first jab, reveals US study

Coronavirus vaccines developed by Pfizer-BioNTech and Moderna proved to be highly effective even after the first shot, a new US study has revealed. The study showed that both the vaccines reduced the risk of infection by 80 per cent over two weeks after the first shot.

After the second shot, the risk of infection dropped by 90 per cent in two weeks, the study additionally found after surveying 4,000 US healthcare workers and first responders. The study proves that the vaccines work soon after the first dose, and are helpful in preventing even asymptomatic cases.

The study, undertaken by the US Centers for Disease Control and Prevention (CDC) observed the ability of vaccines against infections, even asymptomatic ones. The studies and trials undertaken by respective pharma companies did prove its efficacy, but did not take into account asymptomatic cases.

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Some countries are now pushing back giving people the second dose as vaccine shortages continue to slowdown global rollouts of vaccines Even then, US health officials suggest administering two doses to all. The vaccines are based on the mRNA technology which is proving to be effective.

The study accounted for 3,950 participants from six states over a 13-week period from December 14, 2020 to March 13, 2021. Out of these, about 74 per cent had received their first shot, following which tests were undertaken to check for infections without symptoms.

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"The authorized mRNA COVID-19 vaccines provided early, substantial real-world protection against infection for our nation's healthcare personnel, first responders, and other frontline essential workers," CDC Director Rochelle Walensky announced in a statement.

mRNA is a new technology which uses the synthetic version of a natural chemical message to order cells to create proteins that are akin to COVID-19. The immune system then learns to recognise and attack the virus.