Research and studies published by the newspaper revealedThe Wall Street JournalWhat is known as “hybrid immunity”, a combination of exposure to infection and vaccination, has kept deaths low in countries where millions of the population have not been fully vaccinated, during the spread of the highly infectious omicron mutant.
And residents of several countries “severely affected” by the outbreak of the delta mutant last year gained “high levels of protection through infection” (herd immunity).
When the omicron mutant arrived in Asia a few months ago, India and Indonesia had “a huge gap in their defences”, with two-thirds of their populations not yet fully vaccinated.
And it turned out that the residents of such countries emerged from the latest waves of Corona (Omicron) with a small number of deaths, compared to the Delta wave, and in countries where the majority of the population is vaccinated and have better health care systems, such as South Korea, Japan, and Hong Kong.
Epidemiologists say the main reason for this is that the population of developing countries, which was hard hit by last year’s delta wave, acquired “high levels of immunity” during the spread of infection, and that protection appears to have been maintained during the Omicron wave.
Studies conducted in India, Indonesia and South Africa show “a wide spread of antibodies to corona, far exceeding vaccination rates.”
For example, “natural immunity”, which refers to antibodies acquired through infection, was prevalent in Indonesia when the omicron mutant arrived. One study, conducted from October to December of nearly 20,000 Indonesians, found that 74% of unvaccinated Indonesians had protective antibodies against the virus.
During the Omicron outbreak, Indonesia recorded a higher number of infections than during the delta outbreak, but recorded 270 deaths per day during the Omicron, compared to 1,800 cases during the Delta.
In India, deaths during the Omicron wave peaked at an average of 1,100 per day in early February, compared to 4,200 during the peak of the Delta wave in May.
The relatively slow vaccination campaigns raised “fears of another tsunami of infections, increased pressure on hospitals, and increased deaths” during the spread of the omicron mutant, but it was found that herd immunity, acquired from previous mutant, helped dispel these fears.
The scientists explain that “although immunity will wane over time, this gives governments more time to speed up vaccination campaigns before the virus mutates again.”
Some research indicates that immunity to infection lasts longer compared to immunity from vaccination, and it has found that unvaccinated people maintain normal immunity for up to 20 months after infection, while other research shows that immunity wanes from vaccination after a few months.