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?
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.
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.
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.
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.
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.