3rd dose for the non-immunocompromised – is it necessary?

13th November 2021, Dr Chee L Khoo

booster shots?

The success of mass vaccination is demonstrated by the dramatic reduction in case numbers and deaths from Covid-19 infections since the introduction of the covid-19 vaccines worldwide. Countries such as UK, USA, Israel and Singapore started and completed their campaign very early in 2021. Their success has been challenged by the increasing breakthrough in those countries since June 2021.…

Covid-19 vaccine booster for the immunocompromised – who is eligible?

Booster jab, anyone?

10th October 2021, Dr Chee L Khoo

Updated 17th October 2021

You would have caught a bit of the announcement that some people may be due a Covid-19 vaccine booster. As usual, the announcement is not precise or detailed enough and now everyone is confused whether they are the intended target group for the booster. It is not a call to boosters for most vaccinated people.…

Oral anti-viral against Covid-19 – how does it work?

5th October 2021, Dr Chee L Khoo

The media is abuzz with this wonder oral drug for treatment of Covid-19 infection by Merck, Sharp & Dohme (MSD). We are talking about Molnupiravir, the broad spectrum anti-viral agent which inhibits replication of not just Covid-19 but many other viruses in cell culture. What is Molnupiravir? Who amongst the patients with Covid-19 infections will benefit from the drug?…

Covid-19 vaccination booster – why, when, what?

23rd September 2021, Dr Chee L Khoo

Booster anybody?

You have to agree that the covid-19 vaccines have been pretty effective in reducing the case numbers of covid-19 worldwide. However, over the last few months, with the emergence of the delta variant, there have been resurgence of the virus. Is it because delta variant is more contagious? Perhaps, the efficacy of the vaccines has waned as it’s coming up to 6 months for those who had their vaccines earlier in the year.…

Comirnaty vaccine – how safe is it? What about myocarditis?

13th September 2021, Dr Chee L Khoo

mRNA covid-19 vaccines

Phase 3 trials have inherent limitations in assessing vaccine safety because of the small number of participants and the sample population is generally reasonably young and healthy. They are often underpowered to identify less common adverse events. For example, the AZ interventional arm had about 11,000 participants and the interventional arm of the Pfizer Comirnaty vaccine had about 23,000 participants.…

Delta variant – are the vaccines any good?

real world data

26th August 2021, Dr Chee L Khoo

The Delta variant, first identified in India in December 2020, spread rapidly throughout a mostly unvaccinated country and caused massive numbers of cases, hospitalisations, and deaths. It’s now responsible for the outbreaks spreading across the world. This includes countries that have high vaccination rates. In the UK, the Delta variant has spread rapidly.…

Covid-19 vaccines – can we mix and match yet?

8th August 2021, Dr Chee L Khoo


We know that the incidence of thrombocytopaenic thrombosis syndrome (TTS) can occur with the AstraZeneca (AZ) Covid-19 vaccines although it is pretty uncommon. What do you do with patients who had TTS with the first jab and it’s now ready for the next jab? Obviously, they can’t have the second jab with AZ.…

Covid-19 and pregnancy outcomes

7th August 2021, Dr Chee L Khoo

It is always difficult for pregnant women to decide whether to have the Covid-19 vaccine during pregnancy. Understandably, they are concerned about the safety of the vaccine administered during pregnancy. When the pandemic started last year, there were some studies which suggest that Covid-19 during pregnancy is associated with “significantly” poor maternal and offspring outcomes.…

AZ jab 2 at 6 weeks – should we?

23rd July 2021, Dr Chee L Khoo

AZ Jab 2

It’s all too confusing. And annoying. They keep releasing updates in the lay media and says “see your GP to discuss” but did not update us. You will recall that 2 weeks ago the recommendations to have the second AstraZeneca vaccination moved to 6 weeks after the first vaccination in areas with the outbreak which is pretty much all of Sydney.…

AZ Covid-19 vaccine – who shouldn’t have it?

9th June 2021, Dr Chee L Khoo

Covid-19 vaccines

We all know that detailed information relating to Covid-19 is both fluid and rapidly changing. It’s only a mere 3 months since the first reports of thrombosis with thrombocytopaenia (TTS) relating to the administration of the AstraZeneca (AZ) vaccine emerged from Austria. The recommendations as to who should not have the AZ vaccine is constantly being revised as more information comes in from the case reports.…

AZ vaccine related thrombosis – when do you suspect?

13th May 2021, Dr Chee L Khoo

Thrombosis with thrombocytopaenia syndrome (TTS)

Thrombosis with thrombocytopaenia syndrome (TTS) has been reported following vaccination with AstraZeneca (AZ) and Johnson and Johnson (JJ) covid-19 vaccines. It is also called VITT (vaccine-induced immune thrombotic syndrome) and VIPIT (vaccine-induced prothrombotic immune thrombocytopenia). It is rare and primarily occurs in those under 50 years old. Although the government recommend that people under 50 years have the Pfizer vaccine, there are people who are in Phase 1A and 1B who can’t and should not wait for the Pfizer vaccine where supplies are limited.…