Three of the two-dose COVID-19 vaccines -- from Moderna and Pfizer-BioNTech in the United States, and AstraZeneca in Britain -- have been shown in a new study to reduce the chances of hospitalization by more than two-thirds. File Photo by Aaron Josefczyk/UPI | License Photo
Sept. 1 (UPI) -- Currently available two-dose COVID-19 vaccines reduce a person's risk for severe symptoms, "long" illness and hospitalization with all known variants of the virus, a study published Wednesday by the Lancet Infectious Diseases found.
The odds of "long COVID-19," or illness with symptoms that persist for 28 days or more after a positive test, are lowered by more than 50% for people who are fully vaccinated, the data showed.
A person is considered fully vaccinated two weeks after receiving a second dose of either the Pfizer-BioNTech or Moderna vaccines, both of which are available in the United States, as well as the Oxford-AstraZeneca shot, which is available in Britain and elsewhere.
In addition, a fully vaccinated person's risk for hospitalization after infection is lowered by more than two-thirds compared to those who are unvaccinated, the study showed.
Fully vaccinated people who experience "breakthrough" infections also are nearly twice as likely to not have symptoms of the disease, researchers said.
"We are at a critical point in the pandemic as we see cases rising worldwide due to the Delta variant," study co-author Dr. Claire Steves said in a press release.
"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 Steves, a senior clinical lecturer in geriatrics at King's College London.
The people most vulnerable to a breakthrough infection following their first vaccine dose include frail adults age 60 and older and older adults living with underlying conditions such as obesity, heart disease, kidney disease and lung disease, researchers have said.
In all age groups, those living in deprived areas, particularly in densely populated urban settings, were more likely to experience a breakthrough infection before receiving their second vaccine dose.
Studies of vaccine effectiveness against earlier strains of the virus found that they offered more than 90% protection against severe illness, while more recent data suggest they provide less than 70% protection against the Delta variant.
The findings of this study are based on analysis of data from British adults who shared their vaccination and infection status using a mobile app.
Of more than 1.2 million adults who received at least one dose of any of the two-dose vaccines, fewer than 0.5% reported a breakthrough infection more than 14 days after their first dose, the data showed.
Among nearly 1 million adults who received both doses of the two-shot vaccines, fewer than 0.2% experienced a breakthrough infection more than seven days following their last injection.
For those who did suffer a breakthrough infection, the odds of that infection being asymptomatic increased by 63% after one vaccine dose and by 94% after the second dose, according to the researchers.
In addition, a person's risk for hospitalization declined by approximately 70% after receiving one or both doses of the vaccine, and their odds of experiencing severe disease -- having five or more symptoms in the first week of illness -- were lessened by about one-third, they said.
After both doses of these vaccines, the risk for "long COVID-19" is reduced by 50%, the researchers said.
"We can greatly reduce that number by keeping people out of the hospital in the first place through vaccination," Steves said.
"Our findings highlight the crucial role vaccines play in larger efforts to prevent COVID-19 infections," she said.