CDC: Reinfection more likely for unvaccinated who had COVID-19 than for vaccinated

Aug. 6 (UPI) -- People who were infected with COVID-19 earlier in the pandemic, but who opt to not get vaccinated against the virus, are more than twice as likely to get sickened again compared with those who receive the shot, according to data released Friday by the Centers for Disease Control and Prevention.

Among 246 adults age 18 and older in Kentucky initially infected with the coronavirus between October and December of last year and diagnosed with the disease a second time in May or June, 20% were fully vaccinated prior to their second bout, the data showed.

Of 492 adults infected only once, during the initial period, just over 34% were fully vaccinated, the CDC researchers said.

Although the odds of COVID-19 reinfection are low, they are reduced even further in those fully vaccinated -- meaning: two weeks following receipt of the second or last dose of the vaccine -- the agency said.

"If you have had COVID-19 before, please still get vaccinated [as] this study shows you are twice as likely to get infected again if you are unvaccinated," CDC Director Dr. Rochelle Walensky said in a statement released with the results.

"Getting the vaccine is the best way to protect yourself and others around you, especially as the more contagious Delta variant spreads around the country," she said.

Those fully vaccinated among the 738 adults residents of Kentucky included in the analysis received either both doses of the two-shot vaccines from Moderna and Pfizer-BioNTech or the one-dose Johnson & Johnson shot.

All three vaccines have been found to be effective against the Delta variant, which is considered more contagious and may cause more serious illness, the agency said.

A separate analysis of COVID-19 infections in Mesa County, Colorado, also released on Friday, found that the Delta variant accounted for 88% of new cases as of June 5, up from 43% on May 1.

Despite making up less than 3% of Colorado's total population, Mesa County had more than half of the stat's cases as of June 6.

Before the Delta variant took hold in the United States, the available COVID-19 vaccines were effective at preventing serious illness, as measured by hospitalizations, among older adults, according to the CDC.

In another analysis of data for nearly 7,300 adults age 65 to 74, also released Friday and covering recipients between Feb. 1 and April 30, the Moderna and Pfizer-BioNTech vaccines prevented COVID-19-associated hospitalization in 96% of those fully vaccinated, the agency said.

Meanwhile, the one-dose Johnson & Johnson vaccine prevented COVID-19-associated hospitalization in 84% of those fully vaccinated in this age group.

Effectiveness of full vaccination in preventing COVID-19-associated hospitalization among adults age 75 years and older was 91% for Pfizer-BioNTech, 96% for Moderna and 85% for Johnson & Johnson, the CDC said.

"COVID-19 vaccines remain safe and effective [and] they prevent severe illness, hospitalization and death," the agency said in a statement.

"Even among the uncommon cases of COVID-19 among the fully or partially vaccinated, vaccines make people more likely to have a milder and shorter illness compared to those who are unvaccinated," it said.