Effectiveness Gap
The rollout of shots from Pfizer-BioNTech SE and Moderna that achieved efficacy levels of about 95% has raised questions about whether everyone will have access to such high levels of protection.
“The gap isn’t just about access to vaccines,” said Yanzhong Huang, senior fellow for global health at the Council on Foreign Relations. “It’s also about access to effective vaccines.”
One of the shots lower- and middle-income countries are relying on, from AstraZeneca and the University of Oxford, sparked worries in Australia that it may not be effective enough to generate herd immunity. Health authorities there, however, said they believe it will be comparable to the Pfizer and Moderna shots in preventing people from getting seriously ill.
The vaccine developed by the U.K. partners, introduced in the country earlier this month, delivered an average efficacy rate of 70%. That appeared to climb to 80% with a longer gap between doses, based on limited data available, according to regulators. Lengthening that period to as many as three months from one allows more people to get protected faster, while data show the level of antibodies also increases, an AstraZeneca spokesman said.
“An optimized regimen which allows the vaccination of many more people upfront, together with a robust supply chain, means we can have a real impact on the pandemic,” he said in an email.
Four vastly differing protection rates have been released on Sinovac’s shot, ranging from about 50% to more than 90%. The Chinese developer said the lower number seen in a trial in Brazil is due to participants being medical workers facing a high risk of contracting Covid.
“Despite the difference in efficacy rate, they all point to the vaccine’s ability for protection, especially against mid- and severe disease,” Sinovac said.
While the picture is still coming into focus, cleared vaccines are likely to be similarly effective in preventing serious sickness and death, said Takeda’s Venkayya. Where they could diverge is on side effects, the duration of protection and impact on transmission, an even more critical factor in light of new variants, he said.
Even shots with a lower efficacy level could have a considerable impact. U.S. regulators set a 50% threshold for deeming a candidate effective. But they would require a higher percentage of people willing to get vaccinated to achieve herd immunity, Huang said.
If less-effective vaccines are distributed to emerging markets, it could have significant economic implications, too, and “sharpen differences in pandemic outcomes across countries,” Justin-Damien Guenette, a senior economist at the World Bank, wrote in an email.
Many countries are depending on Covax, which aims to deploy vaccines equitably to every corner of the planet. Yet not all lower- and middle-income nations are waiting for a lifeline. Several have questioned whether the program will get the vaccines it needs, the WHO’s Tedros said. Governments such as South Africa and Malaysia are also pursuing their own supply deals through direct talks with manufacturers, and some regions are set to receive Pfizer’s vaccine as well.
‘Losing Patience’
“There seem to be indications that countries are losing patience,” said Huang of the Council on Foreign Relations.
Covax has secured access to almost 2 billion doses, with deliveries due to begin in the first quarter, and set a goal of vaccinating up to a fifth of countries’ populations by the end of the year. That’s far short of the levels of two-thirds or more that many nations are targeting. Some may not get vaccines until 2024, researchers estimate.
The mobilization is ramping up. India, a nation of more than 1.3 billion people, kicked off a massive inoculation drive on Saturday, an effort expected to encounter challenges as it extends into rural areas.
Vaccine advocates have called on rich countries to share while pushing companies to scale up manufacturing capacity. While it’s early, the trends are concerning, Venkayya said.
“Success is defined as getting vaccines to people everywhere,” he said, “and we’re not yet successful in that endeavor.”
—With assistance from Dong Lyu, Anisah Shukry, Mike Cohen and Corinne Gretler.
This article was provided by Bloomberg News.