By Nathan Ohiomokhare
If there are limited vaccine supplies Government Health ministries can increase the gap between the two doses of Covid-19 Vaccines to 6 weeks. This is the most recent guidline from the World Health Organisation (WHO). Recall that the Vaccines from Moderna and Pfizer-BioNTech require a booster dose 3 to 4 weeks after the first dose. But with limited vaccine supplies and a projected slower than expected rate of vaccines production the WHO has considered that countries may need more time to get supplies for the second dose even as ather individuals may still be on the process of being administered the first dose. All vaccination can not occur at the same time or within a short period. There will be cues.
The Advisory Committee on Immunization Practices (ACIP) of the United States Center For Disease Control (CDC) has also issued a similar advisory this month on both Pfizer-BioNTech and Moderna mRNA vaccines. The ACIP also added that though the two mRNA Covid-19 vaccines are Bioequivalent they are not interchangeable. The ACIP also advised against co-adminsitration of the mRNA vaccines with other vaccines due to lack of data.
Several countries facing limited vaccine supplies have informed that they will delay administering the booster shot so that more people can benefit from receiving the first dose. With vaccine supplies still limited, the WHO has called for health workers and the most vulnerable groups to be prioritised.
The Strategic Advisory Group of Experts on Immunisation(SAGE) of the WHO beleives intervals of 21 days for the Pfizer-BioNTech vaccine and 28 days for Moderna are best upheld for maximum efficacy and safety. But after putting prevailing circumstances into consideration SAGE has also advised that in “exceptional circumstances” Health workers may stretch the interval between doses up to 42 days for both the Pfizer-BioNTech vaccine and the Moderna vaccine. SAGE also recommended that the two vaccines should only be administered in settings that can deal with a potential anaphylactic reaction.
The WHO SAGE also advised that in situations where there was a shortage of vaccines, people who had been infected with COVID-19 in the previous six months and therefore likely had immunity could opt to postpone vaccination, but stressed that it was not a recommendation to exclude individuals on that basis.
The spokesperson for the WHO SAGE, Alejandro Cravioto, however, warned in a virtual press briefing that the evidence does not go beyond the six-week cut off.
According to the experts both vaccines are very similar, though storage requirements for the Pfizer vaccine is at -70 degrees Celsius while Moderna doses can be stored at -20 C.
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