Herd immunity talked up despite warnings about early reinfection

GOVERNMENT scientists talked up the prospect of the country building up a “herd immunity” to Covid-19 despite private warnings patients could become reinfected in just three months, The Sunday Telegraph can disclose.

Members of the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) warned that the length of immunity was “unclear” and that just 12 weeks “may be a reasonable point” to be reinfected.

The private warnings were issued on March 13, the same day that Sir Patrick Vallance, the Chief Scientific Adviser, caused controversy when he said the Government’s aim was to “build up some kind of herd immunity so more people are immune to this disease”.

Now it can be disclosed that, on the same day, Nervtag discussed whether there would be a “second wave” of illnesses “due to reinfection”, as they considered whether a person “can be reinfected within a matter of months”.

Meanwhile, Matt Hancock, the Health Secretary, last night announced that up to 20,000 people were being asked to take part in a study to help determine what proportion of the population has already had the infection, the duration of immunity after being infected, and why the virus affects people differently. The study, led by UK Biobank, forms part of the Government’s plans to use “surveillance testing” to help learn more about the virus.

On March 13, discussing previous types of coronavirus, Nervtag said: “There is evidence that in people with mild illness, the antibody response can wane quite rapidly and there is evidence that people can get reinfected and can shed quite robust titers of virus within two to three months.”

One study in Kenya found 28 per cent of patients became reinfected by an earlier type of coronavirus, identified in 2004. Minutes of the meeting, attended by several members of the separate Scientific Advisory Group for Emergencies (Sage), state: “Concerns were raised that the length of immunity is unclear. Evidence from endemic coronaviruses is that after a mild infection antibody response may wane and individuals can become reinfected and shed further virus.

“Three months may be a reasonable point after which susceptibility due to waning immunity may occur in those who suffered a mild initial infection.

“Members agreed that the novel nature of [the current coronavirus] means that immune response may be more robust than for seasonal coronaviruses. Members agreed that although there is uncertainty, reinfection is a possibility that should be considered in modelling, and longitudinal studies to identify reinfections are recommended.”

Two days earlier, David Halpern, of the part Government-owned Behavioural Insights Team, suggested highrisk groups could be “cocooned” until “herd immunity has been achieved in the rest of the population”.

On television, Sir Patrick said herd immunity could be achieved if “about 60 per cent” of the population became infected. He made his initial remarks as part of a defence of decisions to delay drastic restriction measures in order to halt the spread of the virus.

Sir Patrick said: “Our aim is to try and reduce the peak, broaden the peak, not suppress it completely; also, because the vast majority get a mild illness, to build up some kind of herd immunity so more people are immune to this disease and we reduce the transmission, at the same time we protect those who are most vulnerable to it.”

A government spokesman said: “This document makes it utterly clear that at the time this meeting took place, evidence around how long the immunity that antibodies might provide against this virus was unclear. Two months later, evidence is still being gathered and assessed. But it is still too early for a final judgment on this. We have repeatedly made clear that herd immunity has never been the Government’s policy or goal.