Can You Delay Your Second Dose of COVID-19 Vaccine?

COVID -19 Vaccine - Is It Safe To Delay A Second Dose? - DoctorOnCall

The development of a new vaccine for coronavirus disease 2019 (COVID-19) is an impressive achievement, but there has been some controversy going on around the world about the vaccine’s second dose. Based on the stipulation, the second dose should be given to those who have already received the first one.  However, the question of whether the second dose should be pushed back until later to give as many people as possible an inoculation now due to limited vaccine supply. Other questions may arise especially in situations when your appointment of getting the second dose is cancelled. You may have worried about how long the gap between two doses is allowed. Is it safe to delay the second dose of the COVID-19 vaccine? Find out more information through this article.

Is It Safe To Delay The Second Dose Of COVID-19 Vaccine?

COVID-19 is a serious epidemic that is rapidly spreading around the world, and the supplies of vaccines available are not keeping up with the demand. Thus, there are opinions suggesting delaying the second vaccine dose until the number of individuals who have received the first dose is dominant in a population. However, the protection from a single dose of vaccine is still unknown owing to absent research data on its long-term immunity against COVID-19 infection.

Health experts are still discussing the appropriateness of delaying the second dose of the COVID-19 vaccine in order to inoculate more people. Prioritizing the first dose is expected so that more people can receive the first dose earlier, which in turn could hamper the spread of the disease. However, experts also think the risk of more coronavirus mutations may be an impact of the delayed dose. Regarding this matter, in a press conference at the White House in January 2021, US based physician-scientist and immunologist Dr Anthony Fauci warned the public not to delay the second COVID-19 vaccine jab. He said that it could be a catalyst for the spread of new variants by giving weaker immunity to the community. Data also showed that two doses of the vaccine are ten times better than a single dose. 

According to the Malaysian Minister of Science, Technology and Innovation, Khairy Jamaluddin, our country will provide the first and second doses of vaccines of the same type in the COVID-19 immunization program starting on February 26, 2021. The initial phase of the program involved only about 20 percent of the total population of Malaysia.

When Should You Exactly Get a Second Dose of COVID-19 Vaccine?

Centers for Disease Control and Prevention (CDC) recommends that a second dose of COVID-19 vaccine should be given within 3 weeks (21 days) of the first dose for the Pfizer vaccine, and within 4 weeks (28 days) for the Moderna vaccine. If the second dose is not given within that period but does not exceed an interval of 6 weeks (42 days), then a second dose injection can be given without having to repeat the first dose. Giving a second dose earlier than the time schedule mentioned above is not recommended. However, under special circumstances, if a person needs to get a second dose earlier, then a second dose injection is allowed up to 4 days earlier from the given schedule. 

As for the AstraZeneca (Oxford) vaccine, the delay of the second dose up to 12 weeks after the first dose has the potential to work well. It is found that the protective effect of the first dose has not diminished up to 12 weeks thus providing a longer interval between the two doses. This was reported in a scientific paper from Oxford University in early February 2021. However, it is important to note that the results of the paper have yet to be peer reviewed. Regardless, in February 2021, only the Pfizer vaccine has been approved in Malaysia while other vaccines such as AstraZeneca, Sputnik V and Sinovac are still being evaluated.

Why Do You Need Two Doses of COVID-19 Vaccine? 

Vaccine production is designed to build an immunological memory that will enable our immune system to recognize and repel pathogens or viruses that infect the body in the future. A large number of COVID-19 vaccines provide such a response by sending copies of protein from the coronavirus to trigger an immune response. Two doses of vaccine are intended for a maximum benefit where the first dose triggers immunological memory, while the second dose is to amplify it. 

Based on clinical trials performed by each pharmaceutical company, the COVID-19 vaccine is more effective when given in two doses, with relatively long time intervals. A scientific article published in JAMA in early February 2021 stated that when the vaccine was tested, the body's immune system response was found to be relatively weak in the weeks after the first immunization, but it was reported to be stronger after the second dose injection of the vaccine.

Furthermore, further research was urged to be continued by looking at the ability of receiving two doses of the vaccine in preventing COVID-19 infection to a group of volunteers. The results showed that both doses of this vaccine were very effective in preventing infection despite symptoms after the first and second dose injections were reported. The symptoms are a sign of the body's response to the vaccine given. Anyhow, in the study, each volunteer was still given a second dose. Thus, it is still unknown how well the vaccine works if only a single dose is given.


In conclusion, the administration of the second vaccine dose is recommended according to the prescribed schedule. So far, Malaysia plans to not delaying the second dose injection. However, of course, the country is keeping up with the development of research results around the world over time. Any instructions will be issued by the authorities if the method of implementation needs to be modified. This is to ensure that the community gets maximum protection against COVID-19 infection. 

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