New Delhi: The first documented instance of coronavirus re-infection came from Hong Kong this week. It was followed quickly by Belgium and the Netherlands reporting one case each. However, there is no reason for alarm yet, say scientists. Their statement will certainly calm coronavirus re-infection fears.
Concerns are mounting that herd immunity may not be enough to curb the COVID-19 pandemic. Scientists in India and elsewhere said more studies are needed for a reliable inference. Wide conclusions cannot be drawn about re-infection from individual cases, noted Belgian virologist Marc Van Ranst said.
“Since we do not yet know how frequent re-infections are, it is difficult to say what these findings mean for the success of a vaccination campaign,” Ranstsaid. He is a clinical biologist at the academic hospital UZ Leuven in Belgium. He was addressing worries that re-infection might also impact the vaccination programme.
Reports of scientists from the University of Hong Kong documenting the world’s first case of human re-infection created a flutter.
Wednesday, a study in the journal Clinical Infectious Diseases assessed the case of a ‘young and healthy’ patient. He was diagnosed with asymptomatic SARS-CoV-2 infection 142 days after recovering from the first episode.
Following the report from Hong Kong, the case was reported in the media Monday but the research paper was published on Wednesday, two similar reports emerged, one each from Belgium and the Netherlands.
The scientists in the Hong Kong study said it may not be possible to curb the ongoing pandemic with herd immunity, which is when a significant section of the population has recovered and gained immunity against a disease.
“Our results suggest SARS-CoV-2 may continue to circulate among the human populations despite herd immunity due to natural infection or vaccination,” the scientists noted in the study, adding that further research is needed to shed more light on the implications of re-infection for vaccine design.
Immunologist Satyajit Rath asserted that conclusions on the immune system working against the virus cannot be made from individual patient case studies.
“We do not know anything about the interactions of immunity and re-infection in such patients. Especially since there appear to be only three such confirmed cases so far,” Rath, from National Institute of Immunology (NII) said.
Ram Vishwakarma, former director of Jammu’s Indian Institute of Integrative Medicine (IIIM), explained that the human immune system is way too complex to make broad statements on re-infection from individual patient studies.
“Every individual is immunologically different. This can be because of different inherent genetic reasons, or they could be on drugs that suppress the immune system, and the history of the individual cases makes a difference,” Vishwakarma stated.
Commenting on the significance of the study for vaccine discovery, he said any vaccine, irrespective of the current findings, may not be completely protective against infection in all humans.
“Vaccines are basically weakened forms of viruses, and we know already that there is no vaccine which is 100 per cent protective, and they may not have a similar effect on all people,” Vishwakarma noted.
“Similarly, natural immunity against the virus may also not be protective to the same extent and in the same way in all people because the idea of a vaccine is to confer immunity to individuals via a complex web of protection with antibodies, and cells of the immune system. So, a person infected with the virus for the first time, or receiving a vaccine, may not have major protective function from antibodies but may have better immunity via the immune system’s T cells,” added Viswakarma.
What are the long-term health consequences of SARS-CoV-2 infection and what are the correlations of such consequences with the level of the initial illness, and/or with the nature and extent of co-morbidities, are just some questions to be addressed in future studies, according to Rath.
He said the long-term consequences of infection, with respect to antibodies as well as the cells of the immune system such as the memory B and T cell responses are also unknown.
