GIVEN the threat posed by the highly transmissible Delta variant, members of the Vaccine Experts Panel (VEP) yesterday said the target for herd immunity for coronavirus disease (COVID-19) must be raised to 90 percent.
In a virtual press forum organized by the Department of Health, VEP head Dr. Nina Gloriani said the original 70 percent herd immunity target will no longer suffice.
“Before, we are targeting to vaccinate 60 to 70 percent, we may need to raise it to 85 to 90 percent because of this Delta variant, which is a real concern,” she said. “We need to aim higher and do it faster,” she added.
The Delta variant which was first detected in India is now in at least 120 countries. The World Health Organization earlier this month said the number of COVID-19 infections worldwide has grown by at least 12 percent, and attributed the global surge in part to the Delta variant.
Panel member Dr Rontgene Solante said the high transmissibility of the Delta variant makes the wider vaccine coverage more necessary.
“We do have a variant that is highly transmissible. For your protection to be 65 or 70 percent, that will not be enough to target as herd immunity,” said Solante.
“For us to get better immunity at the population level, we should have a higher target since we have this Delta variant,” he added.
To recall, the government has said herd immunity against COVID-19 will be achieved only once 70 percent of the country’s population is fully vaccinated.
The VEP also said it is not in favor of shortening the interval between vaccine doses if only to have more fully-vaccinated Filipinos.
“There is very clear data that if you prolong the interval between doses, the level of neutralizing antibodies is higher,” said Gloriani.
“The thing we know is if the interval is longer, the immune response is really better. In fact, if you prolong it, it may even be better,” said Solante.
Gloriani said having a shorter interval may actually lead to low antibodies being developed by the body against the virus.
“The shorter the interval, it can generate antibodies but it will go down faster compared to longer interval,” said Gloriani.
On Wednesday, the independent OCTA Research Team proposed the cutting of the Sinovac two-dose interval to 14 days, while also shortening the AstraZeneca two-dose interval to eight weeks.
Under the emergency use authorization issued by the Food and Drug Administration, the interval of Sinovac doses must be 28 days, while AstraZeneca shots should be given 4 to 12 weeks apart.
But while they are not in favor of cutting down the interval between doses, the VEP said it is considering recommending booster doses.
“We are looking at that possibility, especially in view of waning immunity of vaccines,” said Gloriani.
Solante, however, stressed that the booster shots will likely be given to immunocompromised individuals. They include those with HIV, cancer, elderly who are taking immuno-suppressing drugs, post-transplant patients, and those with chronic kidney diseases.
“In case we give booster, it is likely to a special population with low antibodies and weak responses to the vaccine,” said Solante.
Earlier, Health Secretary Francisco Duque III said those with weak immune system have the highest chances of being given booster jabs if it will be recommended by the VEP.
