The idea of using herd immunity approach to manage Covid-19 — by allowing immunity to develop in low-risk populations while protecting the most vulnerable — is “a dangerous fallacy unsupported by the scientific evidence”, say a new letter signed by 80 international researchers.
According to the open letter published in the journal The Lancet, the experts stated that it is critical to act decisively and urgently.
The authors acknowledge that ongoing restrictions have understandably led to widespread demoralisation and diminishing trust among the public and that in the face of the second wave of infection there is renewed interest in so-called natural herd immunity approaches.
They stressed that any pandemic management strategy relying upon immunity from natural infections for Covid-19 is flawed.
They explained that uncontrolled transmission in younger people risks significant ill-health and death across the whole population – with real-world evidence from many countries showing that it is not possible to restrict uncontrolled outbreaks to certain sections of society, and it is practically impossible to isolate large swathes of the population.
Instead, they said that special efforts to protect the most vulnerable are essential, but must go hand-in-hand with multi-pronged population-level strategies.
They also stated that there is no evidence for lasting protective immunity to SARS-CoV-2 after natural infection, and warned that this waning immunity as a result of natural infection would not end the Covid-19 but instead result in repeated waves of transmission over several years.
They said that this could place vulnerable populations at risk for the indefinite future, as natural infection-based herd immunity strategies would result in recurrent epidemics, as seen with many infectious diseases before mass vaccination.
Instead, the authors call for the suppression of the virus until the population can be vaccinated.
The authors also warn that natural infection-based herd immunity approaches risk impacting the workforce as a whole and overwhelming the ability of healthcare systems to provide acute and routine care.
They noted that “we still do not understand who might suffer from ‘long Covid’, and that herd immunity approaches place an unacceptable burden on healthcare workers, many of whom have died from Covid-19.