Evidence suggests you should take the second vaccine dose for COVID-19 anywhere between 4-to-12 weeks after the first vaccine dose.
Reason:
1. There are two types of protection that a vaccine gives you.
Efficacy Type 1: How effective is the vaccine against a mild/moderate attack of Covid.
Efficacy Type 2: How effective is the vaccine against a serious attack of Covid (i.e. serious attack = hospitalisation or death).
2. Most of us are more worried about Type 2 i.e. Hospitalisation or death. And not all that worried about Type 1 - i.e. a mild/moderate attack.
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3. The research shows that 21 days after the first vaccine dose the efficacy against Type 2 is a full 100 per cent i.e. you are 100 per cent protected against serious Covid (hospitalisation/death).
But you are only about 65 per cent protected against Type 1 i.e. you still have a 35 per cent chance of getting mild/moderate Covid.
4. After the 1st vaccine - The efficacy of 100 per cent against a Type 2 serious attack lasts 12 weeks at least.
5. After the first vaccine, as you are anyway 100 per cent protected against a serious attack of Covid, the 2nd Vaccine only raises the efficacy against even mild Type 1 Covid attacks (i.e. the protection against mild Covid attack goes up with the 2nd vaccine).
6. The efficacy Type 2 i.e. the protection against mild/moderate Covid gets better the later you take the 2nd vaccine:
After 4 weeks - If the 2nd vaccine is taken 4 weeks after the 1st vaccine, the protection against mild/moderate Covid goes up from 65 per cent to 70 per cent (i.e. there's only a 30 per cent chance of getting a mild/moderate attack).
8 weeks - If the 2nd vaccine dose is taken 8 weeks after the 1st vaccine dose, the protection against mild/moderate Covid goes up to 75 per cent (i.e. there's only a 25 per cent chance of getting a mild/moderate attack).
12 weeks - If the 2nd vaccine dose is taken 12 weeks after the 1st dose, the protection against mild/moderate Covid goes up to 80 per cent (i.e. there's only a 20 per cent chance of getting a mild/moderate attack)
7. Last points: The efficacy of the vaccine takes effect only 21 days after it is taken. All this research data refers to only AstraZeneca. These efficacy per cent refer to persons without co-morbidities.
The percentages are approximate
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