The COVID-19 vaccines of Moderna Inc and Pfizer-BioNtech were found effective in real-world conditions, the Centres for Disease Control and Prevention (CDC) - the United States' national public health agency- said in a report released on March 29.
Both the vaccines were found to be 90 percent effective if two doses of the vaccine were given to the beneficiaries, it said.
In the case of a single dose, the efficacy in real-world conditions was found to be 80 percent, as per the findings of the CDC's 'Morbidity and Mortality Weekly Report'.
On full vaccination - when both the doses have been administered to the beneficiaries - the vaccine was found to be 90 percent effective in even preventing infections that show no symptom, the study claimed.
The findings were based on research involving nearly 4,000 healthcare and other frontline workers in the United States. The volunteers of the study were based in eight different locations of the country.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
The research began in mid-December and continued till mid-March. The vaccinated individuals, who volunteered for the study, were checked by the CDC officials routinely even if they showed no symptoms, the report stated.
Over 62 percent of the volunteers had received both the doses of either Pfizer or Moderna, whereas, 12 percent had taken only a single shot of the vaccine.
"Prospective cohorts of health care personnel, first responders, and other essential and frontline workers over 13 weeks in eight U.S. locations confirmed that authorized mRNA COVID-19 vaccines (Pfizer-BioNTech’s BNT162b2 and Moderna’s mRNA-1273) are highly effective in real-world conditions," the report said.
The result of the CDC study largely validates the findings of the clinical trials, in which Pfizer and Moderna vaccines were found to be nearly 95 percent effective.
"These interim vaccine effectiveness findings for both Pfizer-BioNTech’s and Moderna’s mRNA vaccines in real-world conditions complement and expand upon the vaccine effectiveness estimates from other recent studies and demonstrate that current vaccination efforts are resulting in substantial preventive benefits among working-age adults," the CDC study noted, adding that all eligible beneficiaries should get vaccinated.