1ST SHOT ALONE NOT PROTECTIVE
Researchers in Chile, which mostly uses Coronavac, find that jab No. 1 does not have any relevant effect after 4 weeks
ASTUDY in Chile, which has one of the furthestadvanced vaccination campaigns in South America using mainly China’s Coronavac, has found that a first dose alone does not protect against coronavirus infection.
The study by the University of Chile found inoculation to be 56.5 per cent effective in protecting recipients two weeks after the second dose, and 27.7 per cent effective within the first two weeks.
But for a single dose, efficacy in the 28 days between the first and second dose was only three per cent — on a par with the margin of error in such studies, it said.
Researchers looked at the combined effect of Coronavac, which accounts for about 93 per cent of doses being administered, and the Pfizer-BioNTech vaccine.
It estimated Coronavac’s efficacy in real-life conditions at 54 per cent — in line with trial results in Brazil. The Pfizer jab has been estimated to be about 94 per cent effective in an Israeli study.
Chile has so far given at least one shot to 7.07 million people, and both shots to 4.04 of 15.2 million inhabitants being targeted for vaccination.
Like the rest of Latin America, the country has seen a steep rise in new infections and has surpassed the daily rate of the first wave last year, with more than 8,000 new cases per day.
“Getting vaccinated very significantly decreases the possibility of infection, it does not eliminate it, but it decreases it a lot. Therefore you have to get vaccinated,” University of Chile rector Ennio Vivaldi said.
But it was also clear that the first dose on its own “does not have any relevant effect after four weeks”, which means the recipient was for all intents and purposes just as vulnerable to infection as a non-vaccinated person.
The study estimated that for people between 75 and 79 — targeted in the initial vaccination campaign — there would have been 80 per cent more infections without the vaccine.
For those aged 70 to 74, the percentage dropped to 60 per cent.
In London, Britain yesterday began rolling out its third coronavirus vaccine from United States company Moderna, as questions mounted over jabs from the country’s main supplier, AstraZeneca.
The first jabs of the two-stage Moderna inoculation were injected at a hospital in Wales, in a timely diversification of Britain’s rollout that was hailed by Prime Minister Boris Johnson.
“We have ordered 17 million doses that will be going into arms across the UK in the coming weeks. Please get your jab as soon as you are contacted,” he tweeted.
Supply problems for AstraZeneca had threatened to complicate Britain’s inoculation drive, and concerns are building over a potential link between the jab and rare blood clots among a small number of recipients.
Oxford University said on Tuesday that it had paused a British trial of the AstraZeneca vaccine on children. The university said the trial had posed “no safety concerns”, but that it was awaiting data from Britain’s Medicines and Healthcare products Regulatory Agency (MHRA) before restarting the study.
The MHRA says it is looking into the cases of clotting, amid reports that the regulator may join some countries in the European Union in restricting access in younger age groups.
The MHRA reported over the weekend that there had been 30 blood clotting cases, seven fatal, out of 18 million doses administered in Britain.
The European Medicines Agency is also looking anew at the issue, but so far the World Health Organisation insists the jab is safe.