New COVID variant may change herd immunity target

September 10, 2021
Persons at the National Arena waiting to be vaccinated.
Persons at the National Arena waiting to be vaccinated.
Bisasor-McKenzie
Bisasor-McKenzie
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Chief Medical Officer (CMO) in the Ministry of Health and Wellness, Dr Jacquiline Bisasor-McKenzie, has said that the Government's target to vaccinate 65 per cent of the population by March 2022 may change because of the emergence of new variants of the novel coronavirus.

This after Health and Wellness Minister Dr Christopher Tufton confirmed reports that the Mu variant of COVID-19 is in Jamaica, with 26 of 90 samples testing positive.

"You would have seen that various countries have been relooking at these numbers especially in light of countries that would have achieved over 70 per cent vaccination and would still be seeing an increase in number of cases," said Bisasor-McKenzie at Thursday's COVID conversations briefing. "This is just showing how things are evolving over time. Certainly, when we started out looking at the reproductive rate of the virus at the time and looking at the strain that was there at the time, the prediction was that in the region of 65-70 per cent of persons with immunity, we would have achieved herd immunity. I think that things have changed since that and certainly with the new strains that are there, reinfections that are happening, it is clear that we may have to achieve more than that in order to get immunity, and then there is no guarantee as to how long that immunity will last."

Nearly a month ago, Dr Jarbas Barbosa da Silva, assistant director at the Pan American Health Organization, asserted that achieving herd immunity may require vaccination rates above 70 per cent. Bisasor-McKenzie sought to correct cynics who have questioned the authenticity of reports highlighting the increasing number of COVID-related deaths over the past weeks.

"In everything you do there is a margin of error, and in classifying deaths in some situations it is very clear cut the cause of deaths. But in many situations it is death as a result of. There is some margin of error and clearly there are a lot of persons who have chronic illnesses and even just age-related issues contribute significantly to them having a poor outcome," she said.

As of Wednesday, Jamaica had recorded 74,007 COVID-19 cases. Fatalities now stand at 1,685. The CMO has also warned that despite data suggesting that Jamaica may be turning the corner in relation to a downward trend in the weekly reproductive rate, the measures imposed by the Government will need to continue for several more weeks in order for the numbers to be reduced.

"Any projection in terms of how long, is going to be based on the variants that are in circulation. Delta is very, very transmissible and so that can change how long we take to go down. And then if we get new variants that are transmitting even faster than the Delta then that also can cause a lengthening of this surge. And it also depends on the measures we have in place. We have seen that the restrictions have been put in place and we have seen a decrease in reproductive, we have seen a decrease in positivity rate," she said.

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