Although people who recover from COVID-19 usually gain some immune defenses against reinfection, they get additional protection from vaccines, especially against severe disease, according to two studies. In a separate study, among children under age 5 who were ineligible for coronavirus vaccines, the Omicron variant caused 6- to 8-times more infections than the Delta variant, but severe COVID-19 was less common with Omicron, US researchers found.
One study of 22,566 people in Brazil who had recovered from COVID found that all four vaccines in use there - from Sinovac Biotech, AstraZeneca, Johnson & Johnson, and Pfizer/BioNTech - provided significant additional protection. FILE PHOTO
Effectiveness against infection starting 14 days after vaccination completion ranged from 39.4% for Sinovac's CoronaVac to 64.8% for the Pfizer/BioNTech shots. Effectiveness against hospitalization or death ranged from 81.3% for CoronaVac to 89.7% for Pfizer/BioNTech's vaccine. Among children under age 5 who were ineligible for coronavirus vaccines, the Omicron variant caused 6- to 8-times more infections than the Delta variant, but severe COVID-19 was less common with Omicron, US researchers found.
When Omicron first started to circulate, that rate rose to roughly five to 13 new infections per day among every 2,000 children, the researchers reported on Friday in JAMA Pediatrics.