Recent preliminary research from India may offer some more good news for people who have gotten covid-19 vaccines, even in the face of the more virulent Delta variant. The study found that fully vaccinated people who ended up hospitalized—itself a rare risk among the vaccinated—still had a lower chance of becoming sicker and dying than those who were unvaccinated and in the hospital. Partially vaccinated people, however, seemed to have a similar risk of severe illness and death as the unvaccinated once hospitalized.
The study is a preprint published last month on the website medRxiv. Researchers looked at the clinical outcomes of more than 1,000 hospitalized patients in the town of Hyderabad documented between April 24 and May 31 this year. According to the researchers, over 90% of cases involved the Delta variant of the coronavirus, based on genetic sequencing data.
Two of the most commonly used covid-19 vaccines in India are the Covishield vaccine (the Indian version of the adenovirus-based Oxford/AstraZeneca vaccine) and the Covaxin vaccine, a shot locally developed in India that uses killed coronavirus as its way to train the immune system. Both vaccines are thought to provide decent protection against any illness (upwards of 65% from Delta), and very high protection (upwards of 90%) against severe illness, as do all available covid-19 vaccines—very high, but not perfect.
In the study, there were about 500 hospitalized patients vaccinated with either the Covishield or Covaxin vaccine, which both require two doses for full effectiveness. Despite their hospitalization, though, those fully vaccinated were still better off than everyone else.
They were less likely to worsen to the point of severe illness, to need ventilation, and to die than those unvaccinated, even though the vaccinated group was older in general and had higher levels of other risk factors, the researchers said. They also had higher levels of neutralizing antibodies, a key part of the body’s immune response to the coronavirus. Overall, the researchers found that fully vaccinated people were about half as likely to die than those unvaccinated, with a 1.51% mortality rate vs 3.45% for the latter. Unfortunately, no such reduction was seen in those partially vaccinated (the mortality rate for them was 3.35%).
“Our results demonstrate that both COVISHIELD and COVAXIN are effective in preventing disease severity and mortality against the Delta variant in completely vaccinated hospitalized patients,” the researchers wrote.
This research does have caveats, namely that it’s still preliminary and has yet to undergo the traditional peer review process. And the results are most relevant for people who have gotten these specific two vaccines. But other vaccines in the U.S. have shown similar or greater effectiveness against covid-19, and it does align with other data emerging on the outcomes of vaccinated people exposed to the coronavirus. Multiple studies have suggested that vaccinated people can experience similar viral loads as those unvaccinated if a breakthrough infection does happen, but some have also found that vaccinated people then clear their infection faster. And the odds of a breakthrough infection happening at all still appear to be very low in the fully vaccinated, even from Delta.
The risk of severe illness and hospitalization is rare comparatively for vaccinated people, but if there are high enough levels of transmission in the community, as is currently happening in much of the U.S, then there can still be many vaccinated people who end up hospitalized. For these unfortunate victims, at least there’s reason to believe that vaccination will continue to provide them some level of added protection.