Omicron

• Children under the age of 5 may be eligible to receive additional doses of this season’s vaccine if they have not already completed a three-dose series with previous formulations of a COVID-19 vaccine.
• Pfizer and BioNTech have submitted data for their Omicron XBB.1.5-adapted monovalent COVID-19 vaccine to other regulatory authorities around the world.
• The COVID-19 vaccines (COMIRNATY®) by Pfizer and BioNTech are based on BioNTech’s proprietary mRNA technology and were developed by both companies.
• Report vaccine side effects to the US Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) Vaccine Adverse Event Reporting System (VAERS).

• Shortness of breath, brain fog, lethargy and tiredness, loss of smell or taste are common features of long COVID, as is the development of new conditions such as diabetes, heart disease, stroke, depression and dementia.
• Read more:
  When does COVID become long COVID?
• This and other recently published studies on long COVID show that while symptoms do resolve in many people, their resolution is slow and imperfect.

What did the study find?

• The researchers followed 139,000 people with COVID and almost six million uninfected controls for two years, tracking deaths, hospitalisations and 80 long-term impacts of COVID, categorised into ten organ systems.
• After two years, this “hospitalised” group remained at increased risk of 50 conditions.
• This included a risk of clots and blood disorders, lung disease, fatigue, gut disorders, muscle and joint disorders and diabetes.

Findings from other recent research were similar

• The risk of death was concentrated in the first six months after infection.
• A third, not yet peer-reviewed and smaller cohort study of 341 people with long COVID from Spain, found only 7.6% of them recovered at two years.
• An Australian (not yet peer-reviewed) study followed 31 people who developed long COVID and 31 matched controls who recovered from COVID for two years.
• Finally, a recent whole-body positron emission tomography (PET) imaging and biopsy study showed prolonged tissue level immune-activation and viral persistence in the gut for up to a remarkable two years after COVID.

These studies have some limitations

• It’s important to note the observational studies have some inherent limitations.
• The US veterans cohort studied by Al-Aly is nearly 90% men, with an average age of 61 years, which is different to groups most at risk of long COVID.

We still don’t have treatments for long COVID

• In July 2023, the White House established the Office of Long COVID Research and Practice.
• Two randomised trials are testing whether the antiviral nirmatrelvir-ritonavir (Paxlovid) can treat long COVID are currently recruiting patients.

But it’s still important to prevent COVID (re)infections

• Taken together, these studies on the longevity of long COVID add substantially to the case to fast-track the development of interventions and therapies to prevent and/or cure the condition.
• In the meantime, it’s crucially important to prevent (re)infections in the first place to reduce the future burden of long COVID, already estimated to be greater than 65 million people globally.
• If you suspect you have long COVID, discuss this with your GP, who may refer you to specialised services or multidisciplinary care.

• “Omicron XBB-related sublineages are antigenically distant from prior Omicron strains and continue to account for the vast majority of COVID-19 cases globally.
• Pfizer and BioNTech have also filed an application with the U.S. Food and Drug Administration (FDA) requesting approval of their Omicron XBB.1.5-adapted monovalent COVID-19 vaccine for individuals 6 months of age and older.
• The COVID-19 vaccines (COMIRNATY®) by Pfizer and BioNTech are based on BioNTech’s proprietary mRNA technology and were developed by both companies.
• As with any vaccine, vaccination with COMIRNATY, COMIRNATY Original/Omicron BA.1 or COMIRNATY Original/Omicron BA.4-5 may not protect all vaccine recipients.

• In New Zealand, the government removed all remaining public health measures last week.
• But although the emergency is over and the disease is rapidly becoming endemic, the risk of new variants remains.

The basic reproduction number

• Back in 2020, we heard a lot about the basic reproduction number or R0.
• This is the average number of people someone infects when the whole population is susceptible to the disease.
• With a susceptible population, if R0 is above 1 the disease spreads exponentially.
• This situation prompted governments around the world to implement intensive response measures, including lockdowns, to prevent health systems from becoming completely overwhelmed.

Controlling the disease

• Effective control measures should reduce the number of contacts infectious people have, or the risk of infection per contact.
• That’s certainly true, but how much effect do control measures realistically have for a virus like SARS-CoV-2?
• But the effective reproduction number – the average number of people someone infects at the present time – is much closer to 1.

The maths of immunity

• People may have acquired immunity through vaccination, but the protection vaccines provide against infection with current Omicron variants is relatively low and short-lived.
• The majority of immunity comes from previous infections, including infections in vaccinated people.
• (This doesn’t mean that getting infected to get immunity should ever be a goal, but it is an important side effect).
• If R0=10, the maths is even more dismal: the same control measure only gives a 3% reduction in infections.

Targeted protection

• The susceptible-immune binary is a simplification because immunity is not black and white but shades of grey.
• Interventions targeted towards vulnerable groups are likely to be more effective than blanket measures.
• Importantly, although reducing infection rates in the long term is difficult, vaccines provide direct protection for those who take them and continue to be highly effective at preventing severe disease.
• He is an invited expert member of the Communicable Disease Network of Australia and between January 2020 and May 2022 was an invited expert member of the Australian Health Protection Principal Committee.