New studies from the CDC and Mayo Clinic show vaccination greatly reduces risk of COVID related hospitalization, with protection extending against the omicron variant.
The CDC studies, released March 18, show that coronavirus hospitalizations increased when omicron was the dominant variant, at a weekly rate of 38.4 per 100,000 at peak compared to 15.5 per 100,000 when delta was the primary strain. Vaccination, especially with booster doses, still proved effective during omicron, with hospitalization rates for the unvaccinated 12 times higher than for those who were vaccinated and boosted.
For those who only received the primary series of shots, rates were four times higher than during delta, and for those boosted three times higher. Among those boosted, risk of needing ventilation, or infection resulting in death, was reduced by 94%.
The study found racial disparities in terms of needing inpatient care, with rates among Black adults nearly four times greater than for white adults during the height of omicron.
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The Mayo report, released March 22, found fewer than one in 1,000 people who were vaccinated or previously infected with COVID-19 were hospitalized with a new breakthrough infection. Looking at 106,349 patients 18 and older at Mayo Clinic Rochester, of those who were positive for COVID the hospitalization rate was six in 10,000 for those vaccinated, three in 10,000 for those previously infected but unvaccinated, and one in 10,000 for those both vaccinated and previously infected.
While previous infection offered significant protection, lead study author Benjamin Pollock, Ph.D., notes, “We found these results to be in line with previous studies, although the interpretation shouldn’t necessarily be that natural immunity provides the same protection as vaccination. Rather, this study found that among our primary care population, both natural immunity and vaccine immunity appeared to lead to very low rates of breakthrough hospitalizations.”
Previous studies have had varied results regarding whether previous infection or vaccination is more effective in preventing need for inpatient COVID care, with breakthrough hospitalizations rare for both categories. However, study co-author and Mayo infectious disease physician Dr. Aaron Tande stresses the importance of inoculation.
“I explain to my patients that a COVID-19 vaccine provides additional protection, even if they have been previously infected,” Tande says. “For those who have not been infected, vaccination remains the safest and most reliable route of protection. Because it’s impossible to tell in advance how severe a first infection may be, or who among vulnerable populations the virus may spread to, waiting for natural immunity is a gamble and not a safe alternative.”
COVID-19 illness after vaccination rates for Wisconsin have not been updated by the Wisconsin Department of Health Services since the release of December data, which showed those who had not had the primary vaccine series had a hospitalization rate 10 times higher, and death rate 14 times higher, than those who had at least two doses or an mRNA vaccine or one of a viral vector vaccine.
The COVID vaccine is currently available to those 5 and older, and boosters are approved and recommended for those 12 and older.
Emily Pyrek can be reached at firstname.lastname@example.org.