Relying too heavily on a vaccination programme as an exit out of Covid-19 could backfire, a UCC expert in disease control has warned.
Dr Gerry Killeen said the Brazilian experience, as recently detailed in the scientific publication,, was a forewarning of where Ireland could be if we did not get the virus under control.
Brazilian scientists have raised concern that natural immunity built up from a previous Covid-19 infection may not prevent disease from new and emerging variants.
Covid-19 ripped through the city of Manaus in Brazil last year, with an estimated 76% of its population having antibodies to the virus.
Despite this, the city has faced a second more significant wave of disease since the emergence of a new Covid-19 variant, P1.
Dr Killeen, a founding member of the Independent Scientific Advocacy Group, said the Brazilian experience “cast grave doubts” on relying on vaccines as an exit strategy out of Covid-19.
“In December and January, when the P1 variant emerged in Brazil, Manaus went straight back into a sweeping epidemic that was even worse than the first one,” Dr Killeen said, adding that the scale of disease in Manaus offered the best example of what herd immunity might look like.
The built-up immunity did not prevent disease or “take the edge off” subsequent infection, which was of concern, he said.
Dr Killeen said he was “deeply” concerned about talk of reopening society, and that current measures will not crush the present wave of infection
The response, he said, needs to be fine-tuned to tighten up social contacts as well as risks from travel and rolling out rapid antigen testing to “hunt” for Covid-19 in at-risk essential workplaces, while closing non-essential workplaces, could help.
“On average, the number of contacts per positive case has risen from 2 to 2.4. That sounds small but it actually makes all the difference,” he said, suggesting that getting contacts below 2 was key.
A regional response, Dr Killeen added, should be considered as the centralised approach was flawed and public health doctors should be allowed to manage outbreaks locally.
The fact that Dublin is at “simmering point” while other areas, such as Cork and Kerry, are crushing the Covid curve highlighted the need for a decentralised response.
“Dublin is back at that tipping point and it would take a breath of wind to push it back into epidemic growth,” Dr Killeen said.