What you should know about AstraZeneca’s AZD1222
The first batch of AstraZeneca’s vaccine is sourced from the World Health Organization-led Covax facility
The coronavirus vaccine developed and manufactured by the University of Oxford and British-Swedish firm AstraZeneca is the second vaccine brand to arrive in the
Philippines, next to CoronaVac of China’s Sinovac Biotech.
Codenamed AZD1222, AstraZeneca’s vaccine gained popularity in the Philippines after local government units and the private sector secured millions of its doses through tripartite agreements with the national pandemic task force.
The government announced over the weekend that 525,600 doses of AstraZeneca’s AZD1222 will be shipped to the country soon.
The first batch of AstraZeneca’s vaccine is sourced from the World Health Organization (WHO)-led Covax facility, a global initiative which seeks to ensure equitable access to coronavirus vaccines.
Meanwhile, the doses ordered by local government units and some 200 Philippine companies are expected to arrive in the third and fourth quarter of the year.
What do we know about the vaccine and how does it compare to those being developed by other pharmaceutical firms?
AstraZeneca’s vaccine is developed from an adenovirus dubbed as ChAdOx1, a virus that typically causes colds among chimpanzees.
Researchers have modified the virus so that it can carry a gene of SARS-CoV- 2, the virus that causes Covid-19.
Once injected into the body, the vaccine triggers an immune response, producing antibodies and memory cells that will recognize and fight off the virus.
Adenovirus-vectored vaccines have been in development for a long time, in particular against malaria, HIV and Ebola.
The coronavirus vaccine developed by Russia’s Gamaleya Research Institute, dubbed as Sputnik V, was also developed from adenovirus. It is already being distributed there on an emergency basis, although researchers have yet to release detailed results from their late-stage trial.
Adenovirus-vectored vaccines are also being tested by American multinational corporation Johnson & Johnson, as well as in laboratories in China, Italy, among others.
Similar to Sinovac’s CoronaVac, AstraZeneca’s jab can be distributed to far-flung areas since it only requires normal refrigerated conditions of 2 to 8 degrees Celsius (36 to 46 degrees Fahrenheit), and it could be stored for at least 6 months.
Since it is more accessible and easier to keep, the government is eyeing to distribute it in areas that have no ultra-low temperature freezers, such as provinces in Visayas and Mindanao.
Efficacy and safety
While vaccines from Moderna and Pfizer-BioNTech may have higher efficacy rates than that of AstraZeneca’s — 94 and 95 percent, respectively — the AZD1222 vaccine shows a considerable efficacy rate of 63.09 percent, according to the WHO.
Given in two doses (0.5ml each) intramuscularly, the AZD1222 vaccine is administered on individuals aged 18 years and above with an interval of 8 to 12 weeks.
Longer dose intervals are associated with greater vaccine efficacy.
AstraZeneca’s vaccine gained popularity in the Philippines after local government units and the private sector secured millions of its doses through tripartite agreements.
Researchers have earlier said the first dose of the vaccine posted an efficacy rate of 90 percent, while a combination of two full-strength doses only resulted in 62 percent efficacy.
They speculated that the first dose was better in mimicking the experience of an infection, promoting a stronger immune response. However, other factors such as the size and makeup of the groups that got different doses, may also be at play.
Additional research is needed to understand longer-term potential protection after a single dose, the WHO said.
According to the WHO’s interim recommendations published on 10 February, AstraZeneca’s vaccine is also recommended for use even in countries with more contagious variants.
“Countries should conduct a benefit-risk assessment according to the local epidemiological situation including the extent of circulating virus variants,” the organization said.
On the other hand, no serious side effects were linked to the vaccine.
The Philippines’ Food and Drug Administration (FDA) has previously said a review of AstraZeneca’s trials showed its vaccine caused “transient and mostly mild to moderate” side effects “similar to common vaccine reactions.”
“No specific safety concerns were identified and, of course, this reflects limited follow-up,” FDA director general Eric Domingo said in a press briefing on 28 January.
Prices
The Oxford-AstraZeneca vaccine is said to be among the most affordable vaccine options available in the market.
Estimated at P610 for two doses, the Philippines can have up to 135.24 million people inoculated should it spend its entire P82.5 billion Covid-19 vaccine fund for the purchase of AstraZeneca’s product.
It remains unclear whether the Philippine government and private firms have reserved the jab at such prices.
The private sector and some 40 local government units have secured up to 17 million doses from the British-Swedish vaccine maker through tripartite agreements.
The national government, for its part, is eyeing to receive additional 5.5 million to 9.2 million AstraZeneca shots which will come from the Covax facility.