Santiago, Aug 11 (EFE).- Starting Wednesday, Chilean seniors who have had two doses of Covid-19 vaccine are eligible to receive a third dose.
The campaign was announced last week after a study showed that the effectiveness of the Chinese-made CoronaVac formula – administered to 72 percent of vaccine-eligible Chileans – diminishes significantly six months after the second dose.
“We hope that 2 million people can receive a booster dose during the next four weeks,” President Sebastian Piñera said.
The initial program will begin with people over the age of 86 and will be expanded to include Chileans 56 and up as well as immunocompromised individuals.
For the third dose, Chile is using the Oxford-AstraZeneca vaccine.
In September, the opportunity to get a booster shot will be extended to the entire vaccine-eligible population, the president said.
With more than 82 percent of eligible people fully vaccinated, this nation of roughly 19 million people can boast of having one of the world’s most successful inoculation drives.
Coronavirus has killed more than 36,000 people in Chile and confirmed cases stand at 1.62 million, but test positivity has remained below 2 percent for the last 10 days.
Even so, health experts are concerned about the more contagious Delta variant of Covid-19, which has already been detected in around 80 people in Chile.
Dr. Miguel O’Ryan, an infectologist at the Universidad de Chile’s Biomedical Institute, told Efe that it is “appropriate” to offer a booster to at-risk people who received the CoronaVac, “given that with time, this vaccine has shown a greater decline than others in antibodies.”
Chilean researchers have found that CoronaVac is 65.3 percent effective against infection, compared with 80 percent for AstraZeneca and 95 percent for the Pfizer/BioNTech vaccine.
“The issue of the appropriateness of an extra dose for healthy groups is something that remains under debate, though we hope that the Chilean experience benefits the rest of the world,” O’Ryan said.
Health Minister Enrique Paris said that a third dose has the potential to triple the production of antibodies, while specialists say there may be a gain in efficacy from mixing different vaccines.
Universidad de Talca biochemist Marcelo Alarcon told Efe that some international studies indicate the potential for an eightfold increase in antibodies as a result of combining vaccines.
“Booster doses among the critical population are very important to prevent serious cases,” he said, though adding that making the vaccine available on a universal basis should take priority over administering third doses.
Last week, the World Health Organization called for a global moratorium on third shots until more was done to expand inoculation in places such as Africa, where only 1.58 percent of the continent’s 1.2 billion residents have received the full course of the Covid-19 vaccine and fewer than 4 percent have had at least one dose. EFE pnm/dr