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Vaccination after COVID improves immunity; ivermectin fails major trial

April 1 (Reuters) – The following is a summary of some recent studies on COVID-19. They include research that deserves further study to corroborate the findings and that has not yet been certified by peer review.

Vaccination after COVID-19 improves immunity

Although people who recover from COVID-19 generally gain some immune defenses against reinfection, they gain additional protection from vaccines, especially against serious illnesses, according to two studies published Thursday in The Lancet Infectious Diseases.

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A study of 22,566 people in Brazil who had recovered from COVID found that the four vaccines used there – from Sinovac Biotech (SVA.O), AstraZeneca (AZN.L), Johnson & Johnson (JNJ.N ) and Pfizer (PFE.N)/BioNTech (22UAy.DE) – provided significant additional protection. Efficacy against infection from 14 days after completion of vaccination ranged from 39.4% for Sinovac’s CoronaVac to 64.8% for Pfizer/BioNTech injections. Efficacy against hospitalization or death ranged from 81.3% for the CoronaVac to 89.7% for the Pfizer/BioNTech vaccine.

The second study, using data from more than 5 million people in Sweden, found that “hybrid immunity” from a combination of previous infection and receiving one or two doses of a vaccine offered additional protection for at least nine months. “One-dose hybrid immunity was associated with a 94% additional risk of COVID-19 hospitalization and two-dose hybrid immunity with a 90% additional risk of COVID-19 hospitalization,” compared to natural immunity alone, the researchers said. . Neither of the two studies included patients infected or reinfected with the Omicron variant.

Ivermectin fails, convalescent plasma succeeds

Two landmark trials published Wednesday in the New England Journal of Medicine help settle questions about two controversial therapies touted by many at the start of the pandemic with decidedly mixed results – failure for the anti-parasitic drug ivermectin and success for high-glycine blood plasma. surviving COVID -19 antibodies.

In Brazil, 3,515 patients with COVID-19 symptoms for a week or less and at least one risk factor for severe disease were randomly assigned to receive ivermectin once daily for three days, another treatment or a placebo. Four weeks later, ivermectin failed to reduce the rate of hospitalization or prolonged emergency room visits, the researchers reported. The horse wormer was popular with conservative commentators and anti-vaxxers despite warnings from health officials not to use it to treat COVID.

For the so-called convalescent plasma study, US researchers recruited more than 1,000 mostly unvaccinated adults within eight days of the onset of COVID-19 symptoms. Half of the participants were randomly assigned to receive a convalescent plasma transfusion. Four weeks later, 2.9% of those who received the plasma had been hospitalized with COVID-19, compared to 6.3% of those who had not. After controlling for individuals’ risk factors, the treatment reduced the risk of hospitalization by 54%, the researchers said. “COVID-19 convalescent plasma is available in low- and middle-income countries, has no patent limitations, and is relatively inexpensive to produce… (and likely) less vulnerable to the emergence of resistance to antibodies,” they added.

Omicron infects more small children, but less harmfully

Among children under 5 who were not eligible for coronavirus vaccines, the Omicron variant caused 6-8 times more infections than the Delta variant, but severe COVID-19 was less common with Omicron, discovered by American researchers.

They looked at data collected in 2021 and early 2022 on 651,640 children under age 5, including 66,692 with Delta infections and 22,772 with Omicron infections. When Delta was predominant, two to three out of 2,000 children were infected every day, the researchers calculated. When Omicron first started circulating, that rate jumped to about five to 13 new infections per day per 2,000 children, researchers reported Friday in JAMA Pediatrics. By mid-January 2022, more than 16 out of 2,000 infants were infected with Omicron every day, with the highest infection rates seen in children under 2 years of age.

Children infected with Omicron, however, had a significantly lower risk of serious illness compared to similar children infected with Delta. The results can help think about school attendance, mask use and vaccine implementation for young children, the research team said.

Click for a Reuters graphic on vaccines in development.

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Reporting by Nancy Lapid; Editing by Bill Berkrot

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