By Jenny Ortuoste
Are you fully protected after your first shot of a two-dose Covid-19 vaccine?
Some people seem to think so. Social media is full of posts of persons sharing their experiences receiving their first shot and saying “Protektado na ako!”
But is one shot enough? Experts say it isn’t.
How vaccines work
According to the World Health Organization (WHO), “vaccines reduce risks of getting a disease by working with your body’s natural defenses to build protection.” They prevent us from getting sick.
When you get vaccinated, it stimulates your immune system to respond by:
- Recognizing the invading virus or bacteria;
- Producing antibodies, which are proteins produced naturally by the immune system to fight disease. They are the soldiers of our body’s defense, or immune, system;
- Remembering the disease and how to fight it. If you are exposed to the same virus or bacteria again, your immune system can destroy it before you get sick.
“Once exposed to one or more doses of a vaccine, we typically remain protected against a disease for years, decades or even a lifetime. This is what makes vaccines so effective,” the WHO said.
How Sinovac and AstraZeneca work
The two brands of vaccine being used in the country now are Sinovac and AstraZeneca.
Sinovac’s CoronaVac uses inactivated vaccine technology that works by using killed viral particles to stimulate our bodies to produce an immune response. This vaccine is similar to the flu vaccine.
AstraZeneca uses a harmless, modified adenovirus to deliver a piece of genetic code from a pathogen to mimic an infection. Our cells then make copies of the virus spike protein (the ‘crowns’ on the coronavirus that work like keys into our body’s cells) that prod our immune system to develop a specific immune response to the virus.
How two-dose vaccines work
Both Sinovac and AstraZeneca are two-dose vaccines. Sinovac delivers two doses, four weeks (28 days) apart, while AstraZeneca’s two doses are given between four to 12 weeks apart.
“It typically takes two weeks after you are fully vaccinated for the body to build protection (immunity) against the virus that causes COVID-19,” advised the U.S. Centers for Disease Control and Prevention (CDC).
It also said: “For some vaccines, primarily inactivated vaccines, the first dose does not provide as much immunity as possible. So, more than one dose is needed to build more complete immunity.” Sinovac is an inactivated vaccine.
According to Healthline, “some vaccines require two doses because the immune response to the first dose is rather weak…the first dose of the vaccine starts the process of building up protection,” and the second dose works to greatly reinforce this immune response and protection.
The Australian Department of Health advised: “AstraZeneca COVID-19 vaccines require the full 2-dose course for the best immune response…The second dose encourages the body to create stronger protection (immunity) against the SARS-CoV-2 virus that causes COVID-19.
“Individuals may not have the best protection until 7 to 14 days after their second dose of the vaccine…Because of this, you can still become ill prior to this time and infect others around you, so you should continue COVIDSafe practices. ”
Experts say you REALLY need the second dose
Experts say that for two-dose vaccines such as those of Sinovac and AstraZeneca, the second dose is considered a “booster dose” and is necessary to provide a greater degree of protection overall and against variants.
“Itong booster ay parang paraan para masigurado na ito ay magtatagal at mas mataas [This booster ensures that the effectiveness will last long and be of a higher degree],” Philippine Council for Health Research and Development Executive Director Dr. Jaime C. Montoya said in a Laging Handa public briefing last March 3.
“Kapag binigyan ng booster, mas malaki ang degree of protection [When the booster is given, the degree of protection is higher], not only from disease, but also against the possible variants na pwedeng lumabas.”
Variants are forms of the virus with one or more changes called ‘mutations.’ These changes might affect a virus’ properties, such as transmission (it may spread more or less easily) or severity (it may cause more or less severe disease).
Dr. Montoya also anticipated that more shots might be needed to extend the efficacy of the vaccine.
“In the future, hindi tayo magtataka kung magkakaroon ng third shot o fourth shot, depende sa magiging resulta ng mga pag-aaral na isasagawa tungkol sa epekto ng mga booster na ito,” he said.
[In the future, we should not wonder if there will be a third or fourth shot, depending on the results of the studies being made on the effects of boosters.]
At the Laging Handa briefing on February 16, Philippine Foundation for Vaccination (PFV) Executive Director and founder Dr. Lulu Bravo said it is important that both shots must be taken.
“Dapat kung ano ang inumpisahan mo, dahil dalawang dose ‘yan, ay itutuloy mo pa rin sa second dose,” she said. [Whatever you started with, because that needs two doses, you need to continue with the second dose.]
Dr. Bravo emphasized that vaccines are necessary to control the spread of Covid-19 and its variants, and to be able to return to normalcy.
“Variants are there, it is inevitable and it cannot be controlled unless you control the transmission of the disease that you’re preventing… Will the vaccines do that? Yes, potentially,” she said.
“The vaccines ay nandito, sumasagot sa ating pandemya, para makaligtas ng buhay at para makabukas ng ekonomiya, at makabalik tayo sa ating dating pinagkakatiwalaang buhay.”
[The vaccines are here as a response to the pandemic, to save lives and reopen the economy and allow us to our normal lives.]
