COVID Vaccines : FAQ’s on Delta, Boosters and Timing

vaccines and delta

If you are over 35 yrs old you can click here to register.

If you have already had your first jab, read the FAQ’s below for very useful info about what to do now by Dr Fanaroff.

FAQ’s and concerns around Vaccines and other

These are answers to the questions I’ve been most frequently by patients :

If I’ve had Covid, how long do I need to wait before I have a vaccine?

  • If you had a mild infection, you should wait 30 days after recovery (i.e. 30 days after the 10 days isolation time).
  • If you had a severe infection (requiring Oxygen or hospitalization), you should wait 90 days after recovery to have a vaccine.
  • If you had one dose of Pfizer, followed by a Covid infection a few weeks later, the infection serves as a booster dose and there is no rush to have the second vaccine. You could however have it after 90 days.
  • ** If you are a contact of someone infected with Covid and should be in quarantine, you shouldn’t go for a vaccine until quarantine is up. (A negative test at this time could be a false negative, and you could still be incubating the virus.) This is dangerous both to other people at the vaccine station and potentially to the person having the vaccine.

Is my single dose J&J vaccine effective? Does it work against Delta? I’ve heard of lots of people who were vaccinated getting infected?

  •  This week, J&J came out with data showing that the vaccine is effective against Covid infections from the Delta variant (55 to 60% effective) and offers 85% protection against severe disease (100% after day 49). This is better than the data for the beta (original South African) variant, which is important as delta is the predominant strain we are now seeing.
  • Remember that 60% effectiveness still means that 4 out of 10 vaccinated people can still become infected with Covid-19 (but should have mild infections).
  •  The J&J data showed that the vaccine continues to work over time, with strong responses for up to 8 months (hopefully longer, but this is the length of time that data is available for so far).
  • J&J demonstrated both a strong neutralising antibody response as well as a persistent robust cellular immune response.
  • Sisonke also released a statement on 1st July. They reported that, of the breakthrough infections (positive COVID-19 test more than 28 days after vaccine) : 94% were mild, 4% were moderate and only 2% were severe.
  • Breakthrough infections after the Sisonke trial should be reported on
  • Sisonke also reinforced that immunity from the vaccine increases over time and retains effectiveness against variants of concern, such as beta and delta.

Why are so many people who have had a Pfizer vaccine getting infected?

  • Pfizer is a two dose vaccination regime and we have unfortunately seen many people infected in the first couple of weeks after their first vaccination. This may be because they have contracted COVID in the queues, or because they have let their guards down thinking they are protected, or simply because the delta strain is so prevalent and so contagious.
  • The Pfizer vaccine shows only 33% protection from getting infected after one dose, but 80% protection against hospitalisation after one dose, and 94% protection against hospitalisation from the Delta strain after two doses.
  • Remember that full immunity from the Pfizer vaccine is only achieved two weeks after the second dose.

How long should I wait before getting my second dose of Pfizer?

  • New research from the UK showed that a longer than 3 week dose interval produced better and longer lasting immunity.
  • Taking this into account, as well as the fact that more people could receive at least one dose in a short time, the South African guideline was changed to extend the dosage interval from 21 to 42 days.
  • Some vaccination sites are now using a 35 day interval.
  • As long as your return date is after 21 days and up to 42 days, anywhere in between is a safe and effective interval.

If I had a J&J vaccine, can I have a Pfizer booster to be more protected?

  • Prof Grey and Prof Bekker, the principal investigators from the Sisonke (J&J healthcare worker) trial stated last week that they believed that recommending booster top-ups with another vaccine is premature as the vast majority of breakthrough infections from Sisonke are mild.
  • Several doctors have suggested that when available, booster doses of another J&J or with an mRNA vaccine will help to establish better immunity. Trials with mixing different vaccines are ongoing.
  • However, when available, this booster dose needs to be prioritised for doctors and nurses working in Covid wards and ICUs who are at highest risk.
  • One dose of J&J is good protection against severe illness. *It is much more important at this time for more South Africans to get one vaccination, than for those who have already had the opportunity to have protection from one vaccine to get a booster.

What about the new Sinovac vaccine?

  •  This weekend, SAHPRA registered the third COVID vaccine for emergency use in South Africa, subject to certain conditions, including the final results of ongoing clinical studies. This vaccine was also recently registered by WHO, and there has been a lot of political pressure to register it in this country.
  • Sinovac is an inactivated whole virion, two dose vaccine, administered 4 weeks apart and will be registered for people between 18 and 59 years old.
  • We still await robust studies proving efficacy of Sinovac, particularly against the delta variant.


The greater the numbers of unvaccinated people, the bigger the risk of incubating new, even more contagious forms of the virus. Ursula van der Leyden, the president of the European Commission, stated that “None of us will be safe until all of us are safe”. With this in mind it is incumbent on all of us to be vaccinated when it is our turn, while prioritising those most vulnerable.

Useful related links

Is it just a cold or is it Corona? Read more 
The Covid Delta Variant is driving the 3rd wave and what this means. Read more


Dr Sheri Fanaroff

Dr Sheri Fanaroff

Dr Sheri Fanaroff MBBCh FCFP MFamMed, a Family Physician, practicing in Melrose, Johannesburg. Fanaroff is a member of GGPC (Gauteng General Practitioners Collaboration) which has created a platform for doctors to share resources during Covid-19. Look for #voicesthatcare on the GGPC Facebook page.

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