AZ-Pfizer vaccine mix is "confirmed safe and effective"

Community pharmacists who received 1st dose in April will be receiving 2nd dose mid-July… Guidelines issued to address pharmacists’ concerns etc.

“It is a temporary measure, and other vaccine mixes are not approved”

With community pharmacists who have received their first vaccination of AstraZeneca’s COVID-19 vaccine awaiting their second jab with the Pfizer vaccine this month, the health authorities announced that there are no safety concerns regarding the ‘mix-and-match' of the vaccines.

 

The authorities explained that though mild side effects were observed, no severe adverse events were reported after receiving the vaccine mix, therefore, there are no safety issues pertaining to mixing doses of the two vaccines.

 

Guidelines with the said information was issued by the COVID-19 Vaccination Promotion Team in response to the safety concerns raised by some ahead of the ‘temporary mixed-dose inoculation’ that will be provided to the 76,000 people who are working in vulnerable facilities, flight attendants, healthcare workers, and essential workers that already received their 1st dose with the AstraZeneca vaccine from April to May.

 

The move for this mix and match schedule passed deliberation of the Korea Advisory Committee on Immunization Practice (KAICP) with a review on the efficacy and safety of the mixed-dose vaccination to address the delay of the 835,000 vaccine doses that were initially scheduled to arrive by the end of June through the COVAX facility.

 

In other words, the mixed two-dose schedule that uses the Pfizer vaccine as a second dose is a temporary measure decided upon in consideration of the current supply shortage.

 

Community pharmacists under the age of 50 (born after January 1st, 1972) who already received their first vaccinations will have to receive their second shot with the Pfizer vaccine due to age restrictions that were set on using the AstraZeneca vaccine.

 

However, pharmacists who are 50 years or older (born before December 31st, 1971) may receive the AstraZeneca vaccine if they desire.

 

Reservations for the second dose are automatically made to the same institution at which the individual received their first dose, on the 7th day of the 11th week after his/her first vaccination.

 

Individuals may change their vaccination date in the 11th-12th week period after their first vaccination.

 

They may postpone the date by 1 week at most from the originally scheduled date, and it may not be pulled forwarded to an earlier date.

 

“Other countries such as Germany, France, Canada, Norway, Sweden have been recommending mixing use of mRNA vaccines to those who were first vaccinated with the AstraZeneca vaccine.

 

Also, the safety and efficacy of using the Pfizer vaccine as a second dose was confirmed in people who were first vaccinated with the AstraZeneca vaccine in Canada and Spain,” said the COVID-19 Vaccination Promotion Team.

 

Studies from Spain and Germany have shown that vaccinating with the AstraZeneca-Pfizer mix showed a better immune effect with increased neutralizing activity against the COVID-19 variants than one or two shots of the AstraZeneca vaccine.

 

The team added that a study on this mixed-dose vaccination is also currently underway in Korea and that the initial results will be shared in early July.

 

Regarding the adverse events of the dose-mixing, the team added, “Dose-mixing studies abroad have shown that fever increased when the AstraZeneca vaccine was administered first and followed by Pfizer compared to when a same vaccine was administered both times.

 

The results were also the same for the occurrence of mild adverse events such as fatigue, injection site pain, headaches, and muscle pain, but no serious abnormalities were confirmed." The inoculation schedule for the administration of the mixed second dose will follow the period set during the first vaccination.

 

The mix currently planned is the 1st AstraZeneca-2nd Pfizer vaccine mix, and will be administered with an 11-12 week dosing interval according to the AstraZeneca vaccine’s dosing interval.

 

People who must postpone receiving their second shot while following the AstraZeneca-AstraZeneca vaccine schedule are recommended to receive their shots within 16 weeks, which means the second dose should be administered from July 26th to July 31st.

 

In cases where ‘an individual does not receive their second dose due to fear of mixing vaccines,’ the team said, “The second vaccination, as in the first vaccination, will be administered based on each individuals’ consent, so we cannot force an individual to vaccinate with a different vaccine if he/she is not comfortable receiving the AstraZeneca-Pfizer mix.

 

Those who wish to receive the AstraZeneca vaccine rather than Pfizer’s may be able to receive their shots after August 1st, depending on the supply situation.”