CARPHA: Delta variant means covid19 herd immunity threshold now 95%

File photo: Executive Director of CARPHA Dr Joy St John.
File photo: Executive Director of CARPHA Dr Joy St John.

Caribbean Public Health Authority executive director Dr Joy St John has said with the rapid spread of the delta variant of the covid19 virus, the percentage of the population that is now required to achieve herd immunity has increased from 70 per cent to as high as 95 per cent.

St John was speaking at CARPHA’s vaccine acceptance survey results webinar on Friday.

She said studies are showing that with the delta variant taking hold, countries will need to get as much as 90-95 per cent of the eligible population vaccinated to achieve herd immunity and protect the unvaccinated.

She said the delta variant spreads from one infected person to eight to nine people, as opposed to the alpha (original) variant, which spreads to two to three people, and added that younger people are being affected the most.

“We have good (vaccination) programmes (in the region). We just have to get past hesitancy. The only thing to stop delta is to have that wall of protection with the vaccines,” she stressed.

The study was a cross-sectional one done among social media users aged 18 and older in six CARPHA member states between February 17 and June 18.

A total of 2,302 people from six countries – Barbados, Curacao, Guyana, Jamaica, St Lucia, and Trinidad and Tobago – are included in the survey.

It said 51 per cent of participants had received a covid19 vaccine.

Among the unvaccinated, 46 per cent reported they would get the vaccine if available and 32 per cent said they might. The remaining 22 per cent said they wouldnot get the vaccine.

Overall, covid19 vaccine acceptance – including those who have taken the vaccine and those willing to take it – accounted for 74 per cent. It said 15 per cent were hesitant and 11 per cent reported they would not accept a vaccine.

Participants were also asked whether they would vaccinate their children and elderly parents with the covid19 vaccine.

“The percentage of participants who reported they would vaccinate their elderly parents was higher than those who reported that they would vaccinate their children.”

The report said 52.9 per cent of participants indicated they had no concerns about the vaccine while 47.1 per cent said they did.

“Of those participants who indicated that they had concerns about the covid19 vaccine, ‘I am concerned about the possible side effects of the vaccine,’ – 38 per cent – was the major concern selected.”

The other top concerns indicated participants were concerned the vaccine was developed too quickly and that they did not know enough about it.

Monitoring and evaluation specialist at CARPHA Patricia Smith-Cummings said the results should not be used to generalise vaccine hesitancy in the region. She said while the results have given some insight, it cannot be used definitively and caution should be exercised when referencing the results of the survey

The survey report is available on CARPHA's website at


"CARPHA: Delta variant means covid19 herd immunity threshold now 95%"

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