Gov’t experts advise against shortening gap between doses

The government’s vaccine advisers are opposed to a suggestion by a group of analysts to shorten the interval between the first and second doses of COVID-19 shots to speed up the mass inoculation drive amid the threat of the highly infectious Delta variant of the coronavirus.

Shortening the interval will reduce the vaccines’ effectiveness in preventing deaths and serious illness, according to University of the Philippines (UP) professor Dr. Nina Gloriani, chair of the vaccine expert panel of the Department of Science and Technology (DOST).

She said the gap between doses recommended by the vaccine manufacturers was based on their clinical studies on when the vaccines will produce the optimum immune response.

It might even be better, Gloriani said, to prolong the waiting period to allow the body to build up more protection against the virus.

“A shorter span [between doses] will generate antibodies but [the level] will go down. The amount of antibodies will be high but not much. But the longer the interval, the more [antibodies] there will be and it will take longer before [the level] goes down,” Gloriani said at a press briefing arranged by the Department of Health (DOH) on Thursday.

Widen target instead

Instead of shortening the interval, the panel recommended increasing the target coverage of vaccination in the face of the Delta variant threat.

Instead of targeting 60 million to 70 million people, the panel said the vaccination goal should be 85 million to 90 million.

“We do have a variant that is highly transmissible. It will not be enough just to target 65 percent to 70 percent [of the population for] herd immunity,” said Dr. Rontgene Solante, chief of San Lazaro Hospital’s adult infectious diseases and tropical medicine section and one of the panel members.

While studies indicate the vaccines’ reduced efficacy against the Delta variant and other highly transmissible variants of the virus, the vaccines “continue to be protective especially against the severe form” of COVID-19, the two panel members said.

Booster shots

Gloriani also said the panel hoped to come up by next week with recommendations for booster shots for vulnerable sectors, in view of findings that antibodies produced by COVID-19 vaccines wane after a certain period of time.

“[W]e want to come up with some recommendation soon, maybe by next week, at least for some of our health-care workers and those who are immunocompromised,” she said at a Palace briefing.

Gloriani said a study of the Chinese-made Sinovac Biotech vaccine showed that antibodies produced six months after the second dose had declined.

But Sinovac was not the only vaccine whose antibodies decline over time, she said, adding that a third shot could have a boosting effect.

Solante said that should there be booster shots, these should only be given to the elderly, HIV-positive individuals, cancer patients with HIV and people who take immunosuppressive drugs like post-transplant patients and those with chronic kidney diseases.

Purchase eyed in ’22

Presidential spokesperson Harry Roque said the government was prepared to buy booster shots in 2022.

A provision for the procurement of the booster shots has been included in the budget proposal for next year, Roque said. Finance Secretary Carlos Dominguez III earlier said the government allotted P45 billion for next year’s vaccine procurement.