A CDC scientist said Monday that the data needed to properly evaluate Covid-19 vaccine booster vaccinations for the general population is limited – even if President Joe Biden pressures health officials to delete the vaccinations widespread use early in the week from September 20th.

The presentation by Dr. Sara Oliver at a meeting of the Centers for Disease Control and Prevention Advisory Group suggests the panel may limit its initial endorsement of additional shots to vulnerable groups and healthcare workers.

A nurse vaccinates 15-year-old Sherri Trimble at a vaccination clinic at Health First Medical Center in Melbourne, Florida.

Paul Hennessy | SOPA pictures | LightRakete | Getty Images

Several studies suggest that the approved Covid vaccines may still be effective in preventing serious illness and hospitalization, but may be less effective in preventing infections or mild symptomatic illnesses, according to Oliver. The CDCs The Advisory Committee on Vaccination Practices meets on Monday Consider booster vaccinations for all eligible Americans. The panel is also due to vote on the final approval of the Pfizer vaccine by the Food and Drug Administration.

Since the highly contagious Delta variant first appeared, the vaccine’s effectiveness ranged from 39% to 84%, according to Oliver’s presentation, which referred to several separate studies. A study that looked at health care workers and first responders showed that the vaccine’s overall effectiveness dropped to about 65% in July – up from about 90% in February. Israel dates show Pfizer’s vaccine effectiveness has dropped to just 39% in that country.

Scientists have said that the vaccines become less effective over time, and the Delta variant is a more resilient strain that is able to break through that protection.

According to Oliver’s presentation slides, “it is important to monitor efficacy trends by disease severity over time”.

It was pointed out on the slides that vaccines often require multiple doses. Hepatitis B and HPV vaccinations, for example, require a third dose after six months.

“Vaccines that require more than one dose don’t necessarily mean that an annual booster is required,” Oliver said during the presentation.

Once booster shots are available, nursing home residents, health care providers, and the elderly – the first groups to be vaccinated in December and January – will likely be given priority for the additional vaccinations, according to the CDC slides.

The CDC stressed that vaccinating the unvaccinated should be a “top priority” and giving booster doses to vaccinated individuals should not deter those who remain unprotected from the virus.

The agency also emphasized the importance of vaccine availability around the world.

“An uncontrolled global spread that could lead to new variants threatens the control of the pandemic everywhere,” said Oliver. In addition to global distribution, policy on boosters “should also consider equity in the US population,” she added.

Monday’s meeting comes after President Joe Biden said Friday US regulators are considering giving Covid booster vaccinations five months after completing the primary series and bringing forward the expected schedule for a third vaccination by three months.

Scientists have sharply criticized The Biden government’s urge to distribute booster syringes widely says the data provided by federal health officials are not compelling enough to currently recommend third vaccinations for most of the American population.

The Biden government has publicly stated that the third dose will not be given without FDA approval and a vote from ACIP.