Topline
Although they are not effective in preventing all coronavirus infection, Covid-19 vaccines significantly reduce the chances of severe illness and hospitalizations in rare breakthrough cases according to a Wednesday study in The Lancet Infectious Diseases journal. This is a testament to the importance of vaccination, as hospitals struggle to handle large numbers of unvaccinated patients.
Vaccines offer high levels of protection against serious illness and hospitalization caused by... [+] Covid-19. Los Angeles Times via Getty Images
The Key Facts
According to peer-reviewed data analysis from approximately 2 million people in the U.K., Moderna, Pfizer BioNTech, and AstraZeneca, one or two doses of vaccines decreased the likelihood of hospitalization by 70%. This is compared with 30% for those who had five or more symptoms within the first week. Individuals who are fully immunized have slightly lower odds. Researchers found that breakthrough infections were twice as common in fully vaccinated patients than they were in those who were not vaccinated. They also had half the chance of developing long Covid, a debilitating and lingering disease that can last for many months or even years. The rare Covid-19 cases that were reported by less than 0.5% of those partially vaccinated, and 0.2% of fully vaccinated participants in the study had symptoms that were almost always milder, with the exception of sneezing which was more common among the partially-vaccinated. Researchers also discovered a link between age, breakthrough infections, and frail older adults, particularly those over 60 years old. They were nearly twice as likely to get Covid-19 from one dose of vaccine than the healthy older adults. The researchers found that people living in poor areas were more likely to develop breakthrough infections after their first dose. However, this could also be due to other factors such as living conditions or lower vaccine uptake.
Important Background
Although vaccines have been shown to provide protection against Covid-19 even after one dose, the nature of the shield for those who are infected is still unknown. This study was described by the researchers as the first to examine the characteristics of a Covid-19-related infection after two shots. These findings provide insight into the reason that, despite high levels of coronavirus in the U.S.A, nearly all patients who end up in hospital or die from the disease are not vaccinated. It also provides more evidence that vaccines offer the best protection against Covid-19, even though they are less effective against its delta variant. Booster shots will be more popular in wealthy countries due to the fact that older people are at higher risk for breakthrough infections. Health organizations have criticised the U.S. plan to offer them starting September. This decision has been called unfair by many health organizations and could prolong the pandemic. Many countries have not administered vaccines in a long time.
What we don't know
The study had some limitations. It covered several phases of the dominant coronavirus variants of the U.K., including the rise and fall of alpha and delta. Researchers noted that this makes it difficult to draw solid conclusions. The findings might not be applicable to other variant combinations. Researchers also noted that the U.K.'s vaccination schedule, which had a longer gap between doses than in other countries, could limit the application of these findings to other countries. The researchers also noted that the data is based on self-reported data from Zoe Covid. However, the research team believes the study design allowed for a thorough characterisation of infection.
Continue reading
The risk factors and disease profile of SARS-CoV-2 post-vaccination in UK COVID Symptom study app users: A prospective, community-based, clustered, case-control study (Lancet).
Delta Variant More than Doubles the Risk of Covid Hospitalization. U.K. Study Findings (Forbes).
The Vaccine Protection Declines Within Six Months of Second Covid Shot. Study Warns. But, They Still Work Against Delta (Forbes).
Breakthrough Covid Cases: Rare and Often Mild, But Not Always (NYT).
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