BREAKING! Yale Study Shows That More Severe Breakthrough Infections Are Occurring In Those Infected With the Delta Variant!
Although it was originally claimed that breakthrough SARS-CoV-2 infections tend to be mild, a new Yale research shows that more older adults have developed severe breakthrough cases during the Delta variant phase of the pandemic, particularly after a longer period of time had elapsed since their last vaccination. In some cases, deaths have also resulted from these breakthrough infections.
The study findings found that among the patients with severe or critical COVID-19, the age distribution of patients with breakthrough infections was skewed towards older age groups (mean age 71·5 years) compared with those who were unvaccinated (55·2 years). Furthermore, underlying comorbidities including cardiovascular and lung disease, type 2 diabetes, history of malignancy, and baseline use of immunosuppressive medications were more prevalent in patients with breakthrough infections than in those who were unvaccinated.
Despite these differences, which could potentially portend worse clinical outcomes for the patients with severe breakthrough COVID-19, the study findings found a shorter mean duration of hospitalization (10·8 days vs 13·1 days), lower risk of advanced oxygen or ventilatory support (26 [32%] of 82 vs 72 [51%] of 140 patients), and lower in-hospital mortality (eight [10%] vs 17 [12%] patients) among patients with breakthrough COVID-19 than among those who were unvaccinated.
The alarming shifting landscape of breakthrough COVID-19 cases is likely to involve multiple factors, including demonstrated waning of antibody response after full vaccination and emergence of various Delta subvariants and other SARS-CoV-2 variants. The differences in the incidence of breakthrough cases based on vaccine type is of interest and will need further investigation.
The study findings were published in the peer reviewed journal: Lancet Microbe.
The study team monitored the disease severity among patients hospitalized at the Yale New Haven Health System who tested positive for SARS-CoV-2.
For the period between August and mid-October 2021 ie when the Delta variant accounted for more than 95% of infections in the region, about 371 admitted patients tested positive for SARS-CoV-2, among whom 82 patients (22%), who were fully vaccinated, were severely or critically ill with breakthrough COVID-19 infections.
This alarmingly marks a significant rise in severe breakthrough infections as a percent of total number of patients hospitalized with COVID-19 (which was 1.4% in the same health system between March and July 2021). The current study was conducted before the emergence of the SARS-CoV-2 omicron variant.
The study team also compared vaccinated patients with severe breakthrough cases of COVID-19 to unvaccinated patients. The patients with severe breakthrough cases tended to be older (their average age was 71.6 compared with 55.2 for unvaccinated patients with severe COVID-19 infections), and risk factors including underlying cardiovascular disease and type 2 diabetes were more prevalent among those who were vaccinated. Despite finding that the former had more underlying risk factors for worse clinical outcomes with COVID-19, the vaccinated patients with severe COVID-19 infectio
ns had better clinical courses, including shorter hospitalization length, decreased use of advanced oxygen support, and tended to have lower mortality rates.
Dr Hyung Chun, associate professor of medicine (cardiology) at Yale and senior author of the study told Thailand Medical News, “
Even with the increasing number of fully vaccinated patients developing severe COVID-19 infections, their overall clinical outcomes were better than unvaccinated patients admitted during the same time period, highlighting the efficacy of the vaccines especially in the vulnerable population.”
Importantly how long patients had been vaccinated also appeared to play a key role in the emergence of breakthrough infections.
Dr Chun further added, “There was a clear trend in increasing number of severe breakthrough cases the further out from the time of vaccination. This highlights the importance of booster doses, as the efficacy of the vaccines appear to wane over time.”
The U.S.Centers for Disease Control and Prevention report that around 19% of fully vaccinated people in the United States have received a booster shot as of Nov. 28. Over 42% of fully vaccinated people aged 65 or older have received a booster dose.
Dr Chun notes that breakthrough cases are to be expected and they do not mean that the vaccines aren’t working.
He added, “The vaccines clearly improve clinical outcomes, even if you are sick enough to be hospitalized with COVID-19.”
A critical takeaway from these study findings is that the vaccines are highly effective and that everyone should take booster doses seriously, Dr Chun said.
He said, “Emerging data show that people who received the vaccines in the early stages shouldn’t be going about their lives thinking they’re fully protected against COVID-19. Especially with the emergence of the Omicron variant, we need to reconsider our definition of being ‘fully vaccinated’ to include the booster vaccinations.”
Thailand Medical News would like to add that despite preliminary studies and claims, we still do not have a full perspective of how the current vaccines will protect against disease severity and mortality in the case of the emerging Omicron variant that itself is still evolving.
Please help to sustain this site and also all our research and community initiatives by making a donation. Your help means a lot and helps saves lives directly and indirectly and we desperately also need financial help now.
For more on COVID-19 Breakthrough Infections
, keep on logging to Thailand Medical News.