As the Joe Biden administration stepped up efforts to get more people vaccinated, the US Centers for Disease Control and Prevention (CDC) in three new studies emphasised the importance of Covid shots in preventing death rates, even amid concerns on waning immunity in some populations.
The studies appeared in the agency's Morbidity and Mortality Weekly Report.
A study showed that people who are not vaccinated against the novel coronavirus disease are 10 times more likely to die from the infection compared to those who have taken the shots.
The findings showed that the currently available Covid-19 jabs provide strong protection for most people against hospitalisation and death, even during the delta surge. However, higher hospitalisation and death rates are observed in older age groups, regardless of vaccination status.
For the study, the CDC analysed data on more than 6,00,000 Covid-19 cases, hospitalisations and deaths among people 18 and older by vaccination status, reported from April 4 to July 17 in 13 states and cities.
Vaccine effectiveness against the infection dropped from 90 per cent, when delta had not yet gained significant traction, to less than 80 per cent from mid-June to mid-July, when delta began out-competing all other variants of the virus. Effectiveness against hospitalisation and death showed barely any decline during the entire period, the Washington Post reported.
"Still achieving 80 per cent is a very good number. These vaccines still hold up against a highly transmissible variant," Mehul Suthar, a virologist at Emory University, was quoted as saying.
A second study showed that Moderna's vaccine for Covid-19 is significantly more effective against the Delta variant of the SARS-CoV2 virus than Pfizer or Johnson & Johnson. It suggested that Moderna was 95 per cent effective at preventing hospitalisation among adults ages 18 and older, while Pfizer was 80 per cent effective and Johnson & Johnson 60 per cent effective.
"These real-world data show that vaccines remain highly effective at reducing Covid-19 related hospitalisation and emergency department visits, even in the presence of the new Covid-19 variant," said researcher Shaun Grannis from Indiana University in the US.
For the study, the team analysed more than 32,000 medical encounters from nine states during June, July and August 2021, when the Delta variant became the predominant strain.
The third study which looked at the effectiveness of Pfizer-BioNTech and Moderna found that the mRNA vaccines were 87 per cent effective in preventing hospitalisations and remained highly effective even during delta's predominance.
Vaccine effectiveness in preventing Covid-related hospitalisation dropped to 80 per cent among adults aged above 65 years compared with 95 per cent among those aged between 18 and 64 years.