THURSDAY, Sept. 2, 2021 — If you’re vaccinated against COVID-19, you may still get infected — but the odds you’ll need hospitalization are reduced by about two-thirds compared to unvaccinated people, a new study reveals.
Vaccination also greatly increases the chances that COVID-19 infection will be asymptomatic and halves the risk of long-haul symptoms — those lasting 28 days or more, researchers report in The Lancet Infectious Diseases journal.
“We are at a critical point in the pandemic as we see cases rising worldwide due to the Delta variant. Breakthrough infections are expected and don’t diminish the fact that these vaccines are doing exactly what they were designed to do — save lives and prevent serious illness,” said co-author Claire Steves, of King’s College London.
“Other research has shown a mortality rate as high as 27% for hospitalized COVID-19 patients. We can greatly reduce that number by keeping people out of the hospital in the first place through vaccination,” Steves said in a journal news release.
Relying on the UK COVID Symptom Study, researchers analyzed self-reported data provided from Dec. 8, 2020, through July 4, 2021.
Of the more than 1.2 million adults who received at least one dose of either the Pfizer, Moderna or AstraZeneca vaccines, fewer than 0.5% reported a breakthrough infection more than 14 days after their first dose.
Among the more than 971,000 adults who received two vaccine doses, fewer than 0.2% had a breakthrough infection more than seven days after their second dose, the researchers said.
And for those who did test positive for COVID-19, odds were high that they were symptom-free. The chances of the infection being asymptomatic rose by 63% after one vaccine dose and by 94% after the second dose.
Also, the risk of hospitalization was reduced by about 70% after one or two doses, and the risk of severe disease (five or more symptoms in the first week of illness) was reduced by about one-third, the study found.
The odds of long-haul COVID were reduced by 50% after two doses.
Moreover, people with breakthrough infections who did develop symptoms, such as fatigue, cough, fever, and loss of taste and smell, had less frequent symptoms than unvaccinated people.
“Our findings highlight the crucial role vaccines play in larger efforts to prevent COVID-19 infections, which should still include other personal protective measures such as mask-wearing, frequent testing, and social distancing,” Steves said.
Her team also found that a breakthrough infection after one vaccine dose was nearly twice as high among frail seniors than among healthy older adults.
Kidney disease heart disease, and lung disease were underlying conditions also associated with breakthrough infections in older adults who’d received their first dose but not their second, according to the study.
- The Lancet Infectious Diseases, news release, Sept. 1, 2021
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Posted September 2021