US – Based on findings from a UK research, it was discovered that extending the time between the first and second doses of the Pfizer/BioNTech COVID-19 vaccine boosted antibodies against all variants of the virus tested compared to a short dosing interval.
They found that a longer dosing interval led to two times higher neutralizing antibodies against all variants, including the Delta variant, compared to the short dosing schedule.
The Protective Immunity from T cells to COVID-19 in Health workers study (PITCH) examined how antibody and T cell levels change over time following either a ‘short’ (average of 24 days) or ‘long’ (average of 70 days) interval between the first and second dose of the Pfizer COVID-19 vaccine.
In a separate study published in the Lancet journal, it was found that total antibody levels start to wane six weeks after complete immunisation with Pfizer and AstraZeneca vaccines, and can reduce by more than 50 per cent over 10 weeks.
The researchers from University College London (UCL) in the UK noted that if the antibody levels carry on dropping at this rate, there are concerns that the protective effects of the vaccines may also begin to wear off, particularly against new variants.
UCL Virus Watch study also found that antibody levels are substantially higher following two doses of the Pfizer vaccine than after two shots of the AstraZeneca preventive, known as Covishield in India.
The findings based on data from over 600 people aged 18 and above were consistent across all groups of people regardless of age, chronic illnesses or sex, according to the researchers.
These findings support recommendations that adults who are clinically vulnerable, those aged 70 years or over, and all residents of care homes for older adults should be prioritized for booster doses.
The companies expect to deliver 110 million of the additional doses by December 31, 2021, with the remaining 90 million doses to be delivered no later than April 30, 2022.
Pfizer-BioNTech COVID-19 Vaccine has not been approved or licensed by the U.S. Food and Drug Administration (FDA), but has been authorized for emergency use by FDA under an Emergency Use Authorization (EUA) to prevent COVID-19.
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