Rishard Khan

rishard.khan@guardian.co.tt

The Ox­ford/As­traZeneca COVID-19 vac­cine (AZD1222) is the first of its kind to be ad­min­is­tered in Trinidad and To­ba­go. It is the on­ly vac­cine the coun­try has been able to suc­cess­ful­ly pro­cure so far and the one ex­pect­ed to ar­rive with­in the next two weeks from CO­V­AX. But what is it? 

Type of Vac­cine

It’s a vi­ral vec­tor vac­cine cre­at­ed from a weak­ened ver­sion of a com­mon cold virus and does not cause ill­ness. Once ad­min­is­tered to a per­son, it trains their im­mune sys­tem to recog­nise and fight off the in­fec­tion. It re­quires two dos­es and there is no cur­rent da­ta in­di­cat­ing boost­er shots may be need­ed. Ac­cord­ing to the man­u­fac­tur­er’s prod­uct la­bel, the vac­cine can be ad­min­is­tered with an in­ter­val of 4-12 weeks. While it can be giv­en to peo­ple who were in­fect­ed with the virus, the WHO not­ed that symp­to­matic re­in­fec­tion with­in six months af­ter an ini­tial in­fec­tion is rare. In light of this, it rec­om­mends that those with a PCR-con­firmed in­fec­tion with­in the pre­vi­ous six months wait till the end of this pe­ri­od to get in­oc­u­lat­ed.

Ef­fi­ca­cy

Ac­cord­ing to the World Health Or­gan­i­sa­tion’s (WHO) Strate­gic Ad­vi­so­ry Group of Ex­perts (SAGE), has an ef­fi­ca­cy of 63.09 per cent against symp­to­matic in­fec­tion from the virus. How­ev­er, it not­ed that ef­fi­ca­cy tend­ed to be high­er when the in­ter­val be­tween dos­es was longer. In light of this, the WHO rec­om­mends an in­ter­val of 8 to 12 weeks be­tween the dos­es. 

Trans­mis­sion

None of the cur­rent­ly de­vel­oped COVID-19 vac­cines have been proven to re­duce trans­mis­sion of the virus. How­ev­er ear­ly stud­ies in­di­cate that the Ox­ford/As­traZeneca of­fers some lev­el of this pro­tec­tion.

Who can take it?

It is in­tend­ed to be ad­min­is­tered to peo­ple old­er than 18 years old, es­pe­cial­ly those most at risk for a se­vere in­fec­tion. Ac­cord­ing to the WHO, this in­cludes those over 65 and those with co­mor­bidi­ties. 

Peo­ple of Con­cern

The WHO does not rec­om­mend the jab for those with a his­to­ry of ana­phy­lax­is to any com­po­nent of the vac­cine. It ad­vis­es that peo­ple who have an ana­phy­lac­tic re­ac­tion fol­low­ing the first dose of this vac­cine should not re­ceive a sec­ond dose of the same vac­cine. Out­side of this cat­e­go­ry of peo­ple, no se­vere al­ler­gic re­ac­tions or ana­phy­lax­is were record­ed dur­ing clin­i­cal tri­als. De­spite this, the WHO ad­vis­es re­cip­i­ents be ob­served for 15 min­utes af­ter be­ing in­oc­u­lat­ed “as for any oth­er vac­cine.” It ad­vis­es that preg­nant women on­ly be vac­ci­nat­ed if the ben­e­fits out­weigh the po­ten­tial risks.

There are some cat­e­gories of peo­ple who may not have as ef­fec­tive pro­tec­tion from the vac­cine or may need fur­ther eval­u­a­tion. De­spite the lack of da­ta from clin­i­cal tri­als, it rec­om­mends that they re­ceive the jab once they are el­i­gi­ble for vac­ci­na­tion. This in­cludes per­sons liv­ing with HIV, the im­muno­com­pro­mised, those with au­toim­mune con­di­tions, and those pre­vi­ous­ly di­ag­nosed with COVID-19.