Any hope that herd immunity could become a solution to guiding the country through the coronavirus pandemic has been extinguished by the early findings of a new study. Blood tests taken from a sample of more than 2,000 people in Dublin and Sligo, counties that have the highest and among the lowest levels of infection respectively, have indicated that the vast majority of the population are still susceptible to catching Covid-19.
The early findings show that achieving herd immunity, regarded as anything higher than 60 per cent seroprevalence, is some way off
The initial analysis from the sample study, commenced by the HSE in the middle of last month, shows that less than 5 per cent of the population has been exposed to the virus based on the level of antibodies detected in people tested. This is in line with other countries. Given how this virus can spread and show no signs of symptoms in some of those infected, a seroprevalence study to check who has developed antibodies to fight off future infections is a valuable tool to understand the extent of the pandemic in the State.
The fact that less than half the people written to by the HSE in the study coordinated by the Health Protection Surveillance Centre and UCD’s National Virus Reference Laboratory, agreed to participate is surprising given the collective value of understanding how far infection has spread.
The early findings show that achieving herd immunity, regarded as anything higher than 60 per cent seroprevalence, is some way off and so the virus still poses a real danger to many. It also illustrates how the State’s lockdown was effective in suppressing the virus.
Chasing herd immunity is a dangerous strategy as the pandemic has shown in Sweden, the US and early on in the UK. Even in some of the worst hit areas – the metropolitan area around Madrid, for example – the level of immunity developed with Covid-19 antibodies registered at a percentage somewhere in the low teens.
The results of the Irish sampling may not be surprising, but as the Government prepares its latest advice on international travel, this reminder that so many of us remain vulnerable to the virus should add weight to the case for caution.