The Pfizer and Moderna COVID-19 vaccines provide highly effective protection under real-world conditions, according to a new report from the US Centers for Disease Control and Prevention.

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CNN reported that at full vaccination, the vaccines were 90 per cent effective at preventing infections, including infections that had no symptoms. At a single dose, they were 80 per cent protective, according to the agency's Morbidity and Mortality Weekly Report published 29th March.

The study looked at how the vaccines protected nearly 4,000 healthcare workers and first responders. The volunteers in the study worked in eight locations around the country and had been observed from mid-December to mid-March. The US disease agency tested volunteers routinely regardless of symptoms. The CDC also monitored the volunteers through text messages, e-mails and direct medical reports. The volunteers also did a nasal swab once a week. Most of the volunteers, more than 62 per cent, had received both doses of either a Pfizer or Moderna COVID-19 vaccine. More than 12 per cent had received just a single dose.

Among the 2,961 people vaccinated with one or more doses and the 989 unvaccinated participants, a total of 205 had a positive PCR test for COVID-19, more than 87 per cent of those cases had symptoms. Nearly 23 per cent of the cases sought help from a doctor. There were two hospitalisations, but no deaths were reported. CNN further reported that the results of this study are similar to what scientists saw in clinical trials for the vaccines, but studies like this are important to show how effective the vaccines are, particularly in a population that, through their work, can encounter a large number of people who have COVID-19.

"Reducing the risk for transmissible infection, which can occur among persons with asymptomatic infection or among persons several days before symptoms onset, is especially important among health care personnel, first responders, and other essential and frontline workers, given their potential to transmit the virus through frequent close contact with patients and the public", the report read.

"This study shows that our national vaccination efforts are working. The authorised mRNA COVID-19 vaccines provided early, substantial real-world protection against infection for our nation's health care personnel, first responders, and other frontline essential workers", CDC Director Rochelle Walensky said in a statement. She added that these findings should offer hope to the millions of Americans receiving COVID-19 vaccines each day and to "those who will have the opportunity to roll up their sleeves and get vaccinated in the weeks ahead. The authorised vaccines are the key tool that will help bring an end to this devastating pandemic". The CDC acknowledged that the findings were consistent with other recent studies of partial vaccination following the first dose of the Pfizer vaccine among health care providers.

The studies conducted in the United Kingdom and Israel showed that one dose was about 70 per cent and 60 per cent effective, respectively, against infection with the virus that causes the disease.