(PA­HO, Oct 28, 2021) — "It has noth­ing to do with safe­ty risk when the shelf life of a vac­cine is ex­tend­ed," said PA­HO/WHO Coun­try Rep­re­sen­ta­tive Dr Er­i­ca Wheel­er.  Dr Wheel­er, joined by her Wash­ing­ton based col­league, Dr Maria Luz Pom­bo, Ad­vi­sor, vac­cines and biotech­no­log­i­cal prod­ucts at the Med­i­cines and Health Tech­nolo­gies Unit, pro­vid­ed clar­i­ty on ques­tions around the ex­ten­sion of vac­cines' shelf life in their pre­sen­ta­tion at the Min­istry of Health's week­ly press brief­ing on Wednes­day 21st Oc­to­ber.

In ex­plain­ing PA­HO/WHO's reg­u­la­to­ry role in the ac­qui­si­tion and dis­tri­b­u­tion of vac­cines, Dr Wheel­er said that it was not un­com­mon to ex­tend the shelf life of vac­cines. Changes to ap­proved con­di­tions to vac­cines are of­ten need­ed. Vac­cine shelf life is one of those and is es­tab­lished based on da­ta gen­er­at­ed by man­u­fac­tur­ers over time. Ap­pro­pri­ate­ly, the WHO and oth­er reg­u­la­to­ry bod­ies: the Eu­ro­pean Med­i­cines Agency, the Of­fice of Vac­cines Re­search and Re­view of the Cen­ter for Bi­o­log­ic Eval­u­a­tion and Re­search and The Food and Drug Ad­min­is­tra­tion (FDA) de­cid­ed to ex­tend the shelf life of the Pfiz­er vac­cine from six (6) to nine (9) months, when stored at -90° to -60°C, af­ter a rig­or­ous re­view of the da­ta avail­able. There was a ro­bust rec­om­men­da­tion for the ex­ten­sion.

Dr Pom­bo ex­plained that reg­u­la­to­ry bod­ies grant tem­po­rary au­tho­ri­sa­tion for vac­cines and oth­er med­ical prod­ucts dur­ing emer­gen­cies. Au­tho­ri­sa­tion is based on a rolling re­view of da­ta that man­u­fac­tur­ers gen­er­ate over time. There­fore, it is com­mon to see new in­di­ca­tions, tem­per­a­ture con­di­tions, and shelf-life ex­ten­sions be­cause man­u­fac­tur­ers de­vel­op da­ta while prod­ucts are in use. 

Sta­bil­i­ty stud­ies for vac­cines re­quire sim­u­la­tion of the nat­ur­al con­di­tions that must be stored to meet qual­i­ty stan­dards. In the case of the Pfiz­er COVID-19 vac­cine, those nat­ur­al con­di­tions are -90°C to -60°C for nine months. Nonethe­less, this vac­cine of­fers im­mu­ni­sa­tion pro­grams al­ter­na­tive stor­age con­di­tions with­in the shelf life ap­proved that prac­ti­tion­ers need to be aware of: with­in the o months shelf-life of un­open vials may be stored and trans­port­ed at -25°C to -15°C for a sin­gle pe­ri­od up to 2 weeks, and sta­bil­i­ty stud­ies have demon­strat­ed that up­on re­moval from the freez­er, one can store the undi­lut­ed vac­cine for up to 31 days at 2°C to 8°C, pri­or use. 

In 2020, the var­i­ous reg­u­la­to­ry au­thor­i­ties ap­proved Pfiz­er's COVID-19 vac­cine and the man­u­fac­tur­er gained WHO EUL cer­ti­fi­ca­tion in Dec 2020[1]. Since then, the man­u­fac­tur­er has sub­mit­ted da­ta to the Food and Drug Ad­min­is­tra­tion (FDA) in the USA and oth­er reg­u­la­to­ry au­thor­i­ties glob­al­ly and to WHO to sup­port changes to the con­di­tions ap­proved in the first re­view. Reg­u­la­to­ry bod­ies and WHO have made a con­sid­er­able ef­fort to pro­mote trans­paren­cy of the con­di­tions ap­proved[2],[3],[4] so that prac­ti­tion­ers and pop­u­la­tions are well in­formed about changes that oc­curred based on the da­ta avail­able. 

WHO and oth­er reg­u­la­to­ry bod­ies based the de­ci­sion to ex­tend the shelf life of Pfiz­er's COVID-19 vac­cine on the sub­mis­sion of ev­i­dence of re­al-time sta­bil­i­ty da­ta. This da­ta as­sess­es the qual­i­ty at­trib­ut­es, phys­i­cal ap­pear­ance, and po­ten­cy of the vac­cine.  

Dr Pom­bo al­so not­ed the im­por­tance of im­ple­ment­ing qual­i­ty in­ter­ven­tions to pro­tect the in­tegri­ty of the vac­cines. Health prac­ti­tion­ers and the im­mu­ni­sa­tion pro­gram at the coun­try lev­el must keep records on the new shelf life to en­sure the par­tic­u­lar vac­cine's qual­i­ty, safe­ty, and ef­fi­ca­cy.

PA­HO recog­nis­es the need for fact-based in­for­ma­tion to clar­i­fy ques­tions around the shelf life of COVID-19 vac­cines and the process for ap­proval. Vis­it PA­HO.org for more in­for­ma­tion.