China’s CanSino Covid-19 vaccine wins emergency approval in Mexico
- North American country is first to approve the vaccine developed in association with People’s Liberation Army scientists
- Decision follows Phase 3 international trials showing general efficacy rate of 65.7 per cent for single-shot product
Approval was granted as Mexico scrambles to avoid a shortage of vaccines, with Pfizer/BioNTech and Russian Sputnik supplies not expected to arrive until later this month, throwing the country’s vaccination programme into disarray. So far, Mexico has received 760,000 doses of the Pfizer vaccine, with just 89,000 left, according to Associated Press.
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Mexico signed an agreement last year with CanSino, based in the northeastern Chinese city of Tianjin, for 35 million doses of its vaccine.
The CanSino approval was announced on Wednesday, just days after Pakistani Health Minister Faisal Sultan said on Twitter that interim data from international trials of the vaccine had shown a general efficacy rate of 65.7 per cent.
Sultan said the trials – which involved 30,000 participants and saw 101 infections reported in vaccinated placebo groups – also showed the CanSino shot was 90.98 per cent effective in preventing severe cases of the disease. In the Pakistan subset of the trials, the vaccine had an efficacy rate of 74.8 per cent, he added.
CanSino quoted Sultan in its announcement of the Mexican approval, without giving further details. The company said Mexico’s decision was based on the interim results of phase 3 trials, which are also taking place there. In addition to Pakistan and Mexico, CanSino is holding trials in Russia, Chile and Argentina.
The CanSino vaccine is the second single-dose shot to be approved, after the one by Johnson and Johnson, which has reported an efficacy rate of 65 per cent for its product.
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CanSino is the third Chinese vaccine company to make inroads to the international market for Covid-19 shots, despite scant information about phase 3 trial data from all three. Sinopharm has put the efficacy rate of one of its inactivated vaccines at 79.34 per cent, while Sinovac has recorded an efficacy rate of 50.4 per cent from its trials in Brazil.
CanSino’s vaccine has been approved for military use in China, but not yet for the civilian population. Earlier this week, the PLA donated 500,000 doses of the CanSino vaccine to Pakistan’s military.
The CanSino, Oxford/AstraZeneca, Johnson and Johnson and Sputnik shots are all vectored vaccines, which camouflage different types of adenovirus as the spike protein of the Sars-CoV-2 virus – which causes Covid-19 – to trigger an immune response.
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The use of a common type of flu adenovirus in the CanSino vaccine has raised concerns about its effectiveness, as many people may have pre-existing immunity against it. But, like the Johnson and Johnson vaccine, it has the advantage of only needing one dose. It can also be stored in normal refrigerators, unlike the mRNA vaccines developed by Pfizer and Moderna.
Oxford/AstraZeneca, which also uses an adenovirus as a vector, has reported an efficacy rate of 70 per cent, but the optimal timing and dosage remains unclear.
A major challenge now faced by all vaccines is their effectiveness against new variants of the new coronavirus. A recent study shows the Oxford vaccine is only 10 per cent effective against the South African variant.
