COVID is the worst pandemic in living memory. An international team of scientists has now uncovered another grim distinguishing feature: the COVID pandemic can be considered two back-to-back pandemics, caused by two different serotypes of the same virus.
By focusing on the immune system’s response to viruses, the scientists from Duke-NUS and Singapore, the Global South and Europe determined that SARS-related coronaviruses fall into three serotypes: SARS-CoV-1, SARS-CoV-2 and its earlier Delta and Beta variants, and Omicron. Their findings were published today in the journal hlife.
“The strong selective pressure driven by population immunity favours the emergence of new virus variants. Omicron variants are distinct from their ancestral SARS-CoV-2 virus and can be regarded as a distinct group in the context of antibody immune responses. This implies that pre-existing SARS-CoV-2 immunity is insufficient to prevent current and future infections,” said first author Dr Tan Chee Wah, a principal research scientist with renowned virologist Professor Wang Linfa’s lab in the Emerging Infectious Diseases Programme at Duke-NUS in a media statement to announce the findings.
This was the first time that a comprehensive panel of human serum samples from unvaccinated individuals who had been infected with various SARS-related coronaviruses was used to measure the immune system’s ability to neutralise or eliminate the different viruses.
By focusing on the antibody response, rather than the virus’ genetic sequence, the team found that Omicron — in particular its earlier offspring BA.1, BA.2 and BA.5 — triggers an immune reaction that more closely resembles the reaction stimulated by SARS-CoV-1. The Duke-NUS team, together with international collaborators, had previously shown that Omicron evolved to escape the immune response better than other variants and related coronaviruses in humans, bats and pangolins.
This latest advance confirms that to formulate an effective vaccination strategy, we need to reframe our approach, said co-first author Dr Zhu Feng, a senior research fellow in Wang’s lab: “It is critical for us to understand how newly emerging variants affect our immune system. In this light, serotyping has been a highly useful and proven approach to classify sub-species of viruses such as dengue viruses. The findings will impact future vaccine development and research on immunity testing using antibodies.”
Maintaining the current vaccination technology, which works well for stable viruses like measles and polio, will make eradication of SARS-related viruses in humans an impossible task.
“Viruses such as measles and polioviruses have evolved little to no change in their sensitivity to vaccine-induced immunity for decades,” said Wang, who is the senior author of the paper. “This is not the case for the coronavirus spike protein. Its high structural plasticity, coupled with the vast diversity of animal coronaviruses, makes complete eradication an impossible task with current technology. We need vaccines that can provide protection against the broad spectrum of coronavirus serotypes.”
And Wang’s team would publish their latest advances on this front just days later.