Pfizer on Monday said it was seeking authorisation for third doses of its Covid-19 vaccine to be delivered as booster shots.
This follows a sharp increase in US Covid cases and amid fears of a surge of the Delta variant.
However, World Health Organization officials insisted there was not enough evidence to show that third doses are needed, and said Pfizer should concentrate instead on improving vaccine access around the world.
The WHO director-general, Tedros Adhanom Ghebreyesus, said grotesque vaccine disparities were driven by “greed”.
“We are making conscious choices right now not to protect those in need,” he said, adding that people who have yet to receive a single dose should be prioritised and calling on Pfizer and Moderna to “go all out to supply Covax, the Africa Vaccine Acquisition Task Team and low- and middle-income countries”.
Tedros warned that the number of Covid patients dying was beginning to climb and that the extremely infectious Delta variant was “driving catastrophic waves of cases”.
In the US, confirmed cases rose 47% to 136,351 in the week to Sunday, the largest weekly rise since April 2020, according to data compiled by Johns Hopkins University and Bloomberg. The death toll was 1,629.
Dr Soumya Swaminathan, the chief WHO scientist, said: “At this point … there is no scientific evidence to suggest that boosters are definitely needed.”
More than 3.41bn doses have been administered across 180 countries, according to data collected by Bloomberg, with 334m doses administered in the US.
On Sunday Anthony Fauci, chief medical adviser to President Joe Biden, said he did not rule out the possibility of recommending a third shot. Fauci also deplored what he described as “ideological rigidity” stopping people from getting shots.
Meanwhile, the Johnson & Johnson Covid-19 vaccine has been linked to a rare autoimmune disease.
Reports say the shot has caused instances of Guillain-Barré syndrome, a rare disorder in which the immune system attacks the peripheral nervous system, temporarily paralyzing parts of the body.
The Centers for Disease Control and Prevention (CDC) said it has received about 100 preliminary reports of Guillain-Barré following the one-dose vaccine.
Most of the cases have occurred about two weeks after vaccination and mostly in men aged 50 and older – and that this has not been seen with either the Pfizer-BioNTech or Moderna vaccines.
With just 100 cases reported out of 12.8 million doses administered, this means the condition is very rare occurring in just 0.000781 percent of cases.
The warning is yet another setback for J&J’s vaccine, which has been plagued by pauses, ingredient mix-ups and doses needing to be thrown out.
Guillain-Barré Syndrome is a rare disorder in which the immune system attacks the peripheral nervous system.
It is often triggered by viral or bacterial illnessesses and causes weakness and tingling in the limbs.
As patients’ conditions worsen, this can lead to parts of the body – or in some cases the whole body – being paralyzed.
But J&J said in a statement said it has been in talks with the health authorities in the US about rare cases of Guillain-Barré following the one-dose shot.
“The chance of having this occur is very low, and the rate of reported cases exceeds the background rate by a small degree,” the statement read.