In order to inoculate the entire population, the Singapore government announced that from Wednesday (19 May), those who register for Covid-19 vaccination will get their second dose six to eight weeks after the first. If you recall, the either window between the first and the second dose was three to four weeks.
Now, this strategy of delaying the second dose of vaccine seems to be in the right direction.
A new study states that delaying the interval of the second dose actually allows the first dose of the Covid-19 vaccine to boost its protective power. This happens because the immune system gets more time to respond after the first jab.
New research shows that the levels of antibodies produced to fight off the virus have are higher by 20 percent to 300 percent when the follow-up jab comes later. This has been particularly helpful in distributing more doses of the vaccine to people.
The dose intervals were previously scheduled between three to four weeks after the first inoculation.
The news is a big welcome for Singapore, which is grappling with a small yet significant number of Covid cases in the community. As of May 21, 2021, the Ministry of Health (MOH) Singapore, confirmed there are 40 active cases on the island.
Other Nations Likely To Follow Longer Second Dose Interval
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For the second dose of vaccine, other countries too are likely to increase the interval where the population is huge and doses aren’t enough. The first dose at least prepares your body to fight the infection and lowers the risk of damaging major organs.
Interestingly, the UK was one of the first countries to apply this strategy after cases surged towards late 2020. The country decided to administer the first shot to its high-risk people with the second shot delayed. The decision met with criticism early on but has proven to be smart in hindsight.
Covid-19 affects the upper respiratory system causing damage to the lungs while weakening the immunity levels of the body.
Allowing The First Dose To Mature
Research suggests that the first shot prepares the immune system, allowing it to start making protective antibodies against the virus. The longer it matures, the better the reaction will be to the second jab when it comes months later.
The benefits of a delayed second dose are common across different types of vaccines. The study states that people over the age of 80 were given the powerful mRNA vaccine from Pfizer and BioNTech SE vaccines.
They had an antibody response that was 3.5-fold higher, after being given the second shot in three months instead of three weeks.
Other studies also state that delaying the final shot for nine to 15 weeks helped avoid hospitalisations, infections and deaths. A study from Canada suggests that the biggest benefit came from a six-month delay in administering both doses.
Delaying Protection To Citizens
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The delayed second dose of vaccine raises concerns about whether the risk is worth it. The extended period means that the population at large remains vulnerable to the infection since they aren’t fully immunised.
This is particularly concerning when less potent vaccines are in use, and some are ineffective against the new strains of the virus.
The optimal interval period between doses for AstraZeneca currently stands at 12 weeks. But there is little data on the impact of stretching it to 16 weeks. However, it also remains a major logistical concern to get over a billion people to take the second jab after months.
While there are limitations, getting the vaccine out to people remains a priority in most countries. In Singapore, the task at hand is to administer the dose to 4.7 million people by the end of this summer.
The country is vaccinating about 40,000 people every day. A delayed second dose is helping vaccinate more people in the community.