Hybrid immunization kept Omicron’s mortality low in countries where millions were not fully vaccinated

According to epidemiologists, most of the reason is that developing countries have been hit hard. Delta wave Last year, the infection earned a high level of immunity. And that protection seems to have endured. Studies in India, Indonesia and South Africa have shown that the prevalence of Covid-19 antibody is widespread, well above vaccination rates.

This is a breakthrough for developing countries. The relatively slow-moving vaccination drive, despite the relatively calmness of Omicron, raised concerns that another tsunami could overwhelm the hospital and boost death. However, past Covid-19 infections are far more widespread than the official case numbers indicate and achieve extensive and protective immune coverage sufficient to thwart the most feared consequences. It is useful for. Immunity is weakened, but the government spends more time expanding the scope of vaccines and boosters before the virus mutates again.

Vaccination campaigns are lagging behind in many developing countries as many countries struggle to distribute shots outside major urban areas. In Asia, countries such as India, Indonesia and the Philippines have fully vaccinated half of their population. This is higher than 13% of people living in Africa are vaccinated and 4% are immunized in Nigeria, the most populous country on the African continent. Latin America is better. In many countries, including Brazil and Peru, more than 70% of the population is vaccinated.

Innate immunity, which refers to antibodies acquired by infection, spread in Indonesia when Omicron arrived. According to Pandu Riono, an epidemiologist at the University of Indonesia, a study of about 20,000 Indonesians from October to December found that 74% of unvaccinated Indonesians had protective antibodies. I did.

Based in part on the results, Riono and his colleagues said that as of December, 70% of Indonesians were infected with Covid-19, much higher than 34% of Americans infected so far. I’m estimating. Centers for Disease Control and Prevention.

A serological study by the Government of India conducted last year also showed that 97% of New Delhi residents and 87% of Mumbai residents have antibodies to Covid-19.

“Hybrid immunity, a combination of exposure to infectious diseases and immunization, is high in this part of the world,” said Ramanan, director of the Center for Pathophysiology, Economics and Policy, based at the Public Health Research Institute. Laksi Minarayan says. In Washington DC and New Delhi. “South Asia and Southeast Asia had worse delta waves.”

The situation is similar to South Africa, Where Omicron was discovered It caused a surge in cases, but with relatively few deaths compared to previous waves. In a study published last month in the New England Journal of Medicine, South African researchers found that 36% of people over the age of 12 were vaccinated at least once in Gauteng when Omicron began to circulate. Nevertheless, the Covid-19 antibody was widespread. Of the unvaccinated study participants in the state, 68% had Covid-19 antibodies and 93% of those vaccinated were shown in this study.

According to Our World in Data, Indonesia recently recorded a higher number of cases than during the delta peak, but an average of 270 deaths per day compared to 1,800 in August. In India, the average daily death toll from the Omicron wave was 1,100 in early February, compared to 4,200 at the height of the delta wave in May.

Like much of the world, both countries underestimate the death of Covid-19. However, the images shown by the data are supported by how their healthcare system has progressed. Unlike last year when the hospital ran out of oxygen and medicine, this medical facility is less crowded and many Covid-19 patients are recovering at home. In Jakarta, the capital of Indonesia, cases peaked in mid-February, leaving about 50% of Covid-19 beds free.

“Death isn’t as heavy as it used to be,” said Tri Maharani, a doctor in the emergency room.

Some studies suggest that immunity from infection lasts longer than immunity from vaccination. Dorry Segev, a professor of surgery and artificial health at NYU Langone Health, an academic medical center, led a team that published a research letter to the Journal of the American Medical Association last month. After infection. He said further research during the review showed that this immunity was substantially protective against Omicron. Studies in Israel and the United Kingdom show that vaccination weakens immunity after a few months.

According to the US CDC, people who are fully vaccinated and those who have been previously infected with Covid-19 are at low risk of subsequent infections for at least 6 months.

Alongside active immunization campaigns, innate immunity persistence is a good sign for countries like India and Indonesia, Segev said. “We know that the strongest immunity is a hybrid immunity. Previous infections and vaccinations give you a spectacular level of protection,” he said.

Write in John Emont [email protected]