In addition to the rapid spread of COVID-19 in Europe and the United States, South America is particularly affected, and Chile is facing a severe emergency. Most people in Chile have been vaccinated with The Sinovac vaccine, but the Chilean government has decided to add European and American vaccines, including Pfizer and Astrazeneca vaccines, to those already vaccinated.
Chile launched the world’s fastest mass vaccination campaign in February and now has more than 60 percent, or about two-thirds of the population, getting two doses of the vaccine. They mainly use sinovac vaccines, which account for more than 70% of the vaccinated population in Chile. However, according to a study released by Chile’s Ministry of Health on Wednesday, the effectiveness of sinovac’s vaccine in preventing symptomatic infections was 67 percent between February and April, but dropped to 58.5 percent in a retest in July.
The latest Real World Data released by Chilean health authorities on Wednesday showed that Sinovac’s vaccine was 58.5 percent effective in preventing symptomatic diseases, Reuters and several foreign media reported. The Chilean authorities also noted that the effectiveness of the vaccine would diminish over time and with the spread of different strains of the virus. In a televised address, Chilean President Sebastian Pinera said his government had decided to start a booster campaign for people who had already received two doses of the Sinovac vaccine.
The vaccine prevented 86 percent of hospitalizations, 89.7 percent of transfers to intensive care units and 86 percent of deaths, Chilean health official Rafael Araos said at a press conference on Wednesday. In April this year, the same study found that Sinovac’s vaccine was 67 per cent effective in preventing symptomatic disease, 85 per cent effective in preventing hospital admissions and 80 per cent effective in preventing deaths, indicating an increased ability to prevent the more serious effects of the virus but a reduced ability to prevent symptomatic disease.
But he explained: “Vaccine protection will diminish over time, especially as more mutant viruses, such as Delta, emerge and spread. “If Delta spreads more and the vaccine response weakens, we could see an accelerated decline in vaccine effectiveness.”
In a world-shaking speech at the end of July, Pfizer CEO Albert Bourla admitted that the effectiveness of Pfizer’s vaccine would decline over time, dropping to 84 percent after about four to six months after the second dose. The Pfizer study shows that the situation has affected the effectiveness of preventing severe hospitalization and recommends a third dose of booster.
Chile will begin additional astrazeneca vaccinations on Wednesday, starting with the first batch of 55-year-old citizens who received the vaccine on March 31. Paula Daza, Chile’s deputy health minister, said that, so far, the booster doses have only been given to people who have already been vaccinated by Sinovac, which accounts for 90% of the population.
According to the latest study released by Pfizer, protection from the vaccine was strongest at 96.2 percent between one week and two months after the second dose. But remarkably, vaccine effectiveness decreased by 6 percent every two months. The effectiveness was close to 84% after four to six months, Bourla noted, noting that the study had not been peer-reviewed.
Chile joined the United States, Germany, France and Israel in getting additional vaccinations, despite calls by the World Health Organization (WHO) for a moratorium to allow more people in countries with low global vaccination rates to get the first dose. The number of confirmed cases worldwide has topped 204 million and the number of deaths has topped 4.32 million. More than 36.13 million cases have been confirmed and more than 618,000 deaths have been reported in the United States. India has more than 32.03 million confirmed cases, while Brazil has 20.21 million cases in total.
Pfizer’s German partner BioNTech (BNT) said a third additional dose of the existing booster vaccine so far appears to be more effective than the new vaccine developed against the mutant strain. Preliminary clinical trials in Israel show that side effects from the third dose of the vaccine are roughly the same as those from the second, with some people experiencing fewer side effects.