London – People infected with the Omicron variant of the coronavirus may face less risk of severe illness and hospitalization than those who catch Delta, a new study out of South Africa, which has not yet been peer reviewed, said Wednesday. But scientists warned that the findings could be a result of high levels of population immunity in South Africa due to previous coronavirus infections, and not an indication that Omicron is less severe. The study found that people in South Africa who were diagnosed with Omicron between October 1 and November 30 were 80% less likely to be hospitalized than those diagnosed with another variant during that period. Once in the hospital during that period, however, the patients — no matter which variant they were diagnosed with — were just as likely to develop severe disease. But compared to patients who were hospitalized with Delta between April and November, those hospitalized with Omicron in October and November were 70% less likely to develop severe disease. "It is difficult to disentangle the relative contribution of high levels of previous population immunity versus intrinsic lower virulence to the observed lower disease severity," the study said. The data "suggest that this reduced severity may be in part a result of high levels of population immunity (due to natural infection and/or vaccination.)" South Africa, which has low vaccination rates compared to the United States, was hit hard by previous waves of the coronavirus, with an estimated 60% to 70% of the population contracting COVID-19. Those who recovered would most likely have developed a level of natural immunity, their bodies producing COVID-fighting antibodies and T-cells. One of the study's authors, Professor Cheryl Cohen of the National Institute for Communicable Diseases, said the study's findings could probably be generalized to other countries in sub-Saharan Africa that had seen similarly high levels of previous infection. "What is unclear is whether the picture will be similar in countries where there are high levels of vaccination but very low levels of previous infection," she said at a press conference. "In many high-income countries, most of the immunity that currently is prevalent is because of vaccine-induced immunity, unlike in South Africa where most of it is probably through natural infection," Professor Shabir Madhi, a vaccinologist at Wits University in Johannesburg, told CBS News' Debora Patta in a previous interview. "So, whether the same thing transpires in the U.S. and in the U.K. — where you get this uncoupling of infections and severe disease — I think that remains to be tested," he said. There are also other differences between South Africa's population and that of the United States. People in South Africa are younger, with a median age of 27.6 years compared with a median age of 38.1 in the United States. Hospitalizations as a result of Omicron might occur at different levels in countries with older versus younger populations, BBC News reported. Results from a study last week out of the United Kingdom, which has a much higher vaccination rate than South Africa (as well as a much older population) and is also going through a major wave of Omicron infections, showed there was no sign that the new variant was less severe than Delta. That study has also not been peer reviewed, and hospitalization data from Britain is very limited. Professor Paul Hunter, who teaches medicine at Britain's University of East Anglia, said that while the South African study was important, it was still hard to know whether the lower hospitalization rates in the country were due to Omicron being less severe than Delta. "To a certain extent this does not matter to the patient who only cares that they won't get very sick," Hunter told the Reuters news agency. "But it is important to know to enable improved understanding of the likely pressures on health services."What does this mean for countries like the U.S.?
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