Targeting the Spike Protein
Pfizer’s JN.1 booster (and Moderna’s, though the TGA has not approved this one at this stage) is based on mRNA technology. This technology instructs our cells to produce a specific protein – in this case SARS-CoV-2’s spike, a protein on the surface of the virus that allows it to attach to our cells.
This helps the immune system produce antibodies that recognise the spike protein and interfere with the virus getting into our cells.
So Who Should Get Vaccinated, and When?
Updating vaccines to deal with mutating viruses is not a new concept. It has been happening for the flu vaccine since around 1950.
We’ve become accustomed to getting the annual flu vaccine in the lead-up to the winter cold and flu season. But, unlike influenza, COVID has not settled into this annual seasonal cycle. The frequency of COVID waves of infection has been fluctuating, with new waves emerging periodically.
COVID is also more transmissible than the flu, which presents another challenge. While numbers vary, a conservative estimate of the reproduction number (R0 – how many people will one person will go on to infect) for JN.1 is 5. Compare this to seasonal flu with an R0 of about 1.3. In other words, COVID could be four times more transmissible than flu.
Add to this immunity from a COVID vaccination (or a previous infection) begins to wane in the months afterwards.
So an annual COVID booster is not considered enough for some more vulnerable people.
Making Sense of the Advice
A vaccine that targets JN.1 should provide good protection against the Omicron sub-variants likely to be circulating in the coming months.
A few things need to happen before the JN.1 shots become available, such as the Australian Technical Advisory Group on Immunisation providing guidance to the government. But we can reasonably expect they might be rolled out within the next month or so.
If they hit doctors’ offices and pharmacies before Christmas and you’re due for a booster, the holiday period might be added impetus to go and get one, especially if you’re planning to attend lots of family and social gatherings over summer.
In the meantime, the XBB.1.5 vaccines remain available. Although they’re targeted at an earlier Omicron sub-variant, they should still offer some protection.
Conclusion
Regular COVID boosters are recommended for people who are over 65 or medically vulnerable. For young, healthy people who may be wondering, “do I need a COVID booster at all?”, having one annually is sensible. Although you’re less likely to get very sick from COVID, it’s possible. And, importantly, vaccines also reduce the risk of developing long COVID.
FAQs
Q: Why do we need another type of COVID booster?
A: We need to keep up with the rapidly evolving virus, SARS-CoV-2, by updating our vaccines to target new variants.
Q: Who should get vaccinated, and when?
A: The recommendation varies depending on age and medical vulnerability. For adults aged 65 to 74, a booster is recommended every 12 months, but they’re eligible every six months. For adults over 75, a shot is recommended every six months. Adults aged 18 to 64 are eligible every 12 months, unless they have a severe immune deficiency.
Q: Will the new booster stop me from getting infected?
A: No, vaccines do not necessarily stop you from becoming infected. However, they do reduce the risk of severe illness and long COVID.
Q: How often should I get a COVID booster?
A: The recommendation varies depending on age and medical vulnerability. For adults aged 65 to 74, a booster is recommended every 12 months, but they’re eligible every six months. For adults over 75, a shot is recommended every six months. Adults aged 18 to 64 are eligible every 12 months, unless they have a severe immune deficiency.
