(Art by Christine Angelie P. Orines/ The Varsitarian)

The world’s best shot against Covid-19 often comes in two doses.

Most of the currently available Covid-19 vaccines—except the one developed by Johnson & Johnson—are administered in two jabs.

What’s the difference between the two doses?

There is a specific interval between the administration of the two jabs, depending on the vaccine brand.

The job of the first dose is to allow the body’s immune system to recognize the antigens or the proteins that stimulate the production of antibodies.

The second dose, on the other hand, acts as a “booster” to ensure that a person’s immune system develops a memory response against Covid-19 should the body encounter it again.

Why is there an interval between two vaccine doses?

President Rodrigo Duterte completed his Covid-19 vaccination using the Sinopharm vaccine on July 12. His second Sinopharm vaccine dose was given 70 days or 10 weeks after his first jab.

The World Health Organization (WHO) recommends a three-to-four-week interval in administering two Sinopharm doses.

Palace spokesman Harry Roque said that the chief executive’s second dose was given late based on the advice of his doctor.

However, according to the US Centers for Disease Control and Prevention (CDC), the second dose should be administered as close to the recommended interval as possible. Administering it earlier than recommended is discouraged.

Most two-dose Covid-19 vaccines follow the recommended three-to-four-week interval.

(By Jan Kristopher Esguerra/ The Varsitarian)

For the Sinovac and Sinopharm Covid-19 vaccines from China, the WHO said that past the three-to-four-week interval, the second dose be given at the “earliest possible opportunity.”

The Pfizer-BioNTech Covid-19 vaccine follows a 21-day interval between doses. Moderna and Bharat BioTech’s vaccines both have 28-day intervals for their two doses.

Gamaleya’s Sputnik V is another two-dose Covid-19 vaccine that follows a three-week interval schedule. The second dose of the AstraZeneca vaccine is administered within two to three months from the first shot.

Single shot

The Johnson & Johnson Covid-19 vaccine, the only single-dose vaccine in the world, is a viral vector vaccine that uses a modified and harmless version of a different virus (the adenovirus which normally causes the common cold) to deliver immune response instructions to the body’s cells.

Results of early phase clinical trials involving over 40,000 participants showed the development of a strong immune response in preventing Covid-19 at 85 percent 28 days after inoculation.

Last July 1, Johnson & Johnson announced that their vaccine was found to be effective against the more transmissible Delta variant based on a small, early study conducted.

The Philippines has 3.2 million doses of the Johnson & Johnson vaccine so far. Katherine Anne L. Escarilla


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