The Omicron variant, was first detected in Botswana. It is called a variant as it has up to 59 mutations throughout its genome. 36 of these mutations occur in the spike protein, where the current series of mRNA vaccines target. These mutations change the spike protein on the surface of the virus, which may allow the Omicron variant to evade the body’s defences.
The Omicron variant was first described as a “variant of concern” by the World Health Organisation, on 26 November 2021. As at 19 December 2021, Omicron had been identified in over 89 countries with significant surges on infections in most. The French press (AFP) reported that the total number of COVID-19 cases registered worldwide passed 300 million last Friday with the world recording 13.5 million cases in the last week.
The best defence against COVID-19 is a full dose of vaccine, followed by a booster dose several months later. However, vaccinations alone will not slow Omicron. There has been unanimous support amongst the experts for continued adherence to public health prevention measures including social distancing, improved ventilation, hand hygiene and masks. It is not a pick and choose phenomenon, where an individual may choose to only wear a mask. Everyone must follow all possible measures.
Boosters have become necessary as research from Israel and the USA had revealed that immunity against SARS-CoV-2 coronavirus wanes over 6-8 months. Boosters are able to restore antibody levels closer to their peak levels, as such providing more robust protection. The Australian Technical Advisory Group on Immunisations (ATAGI) has determined that the evidence indicates that booster doses are likely to increase protection against the Omicron variant. However, ATAGI have also stated that the booster doses are unlikely to be sufficient to avert the surge of cases. The boosters will serve to protect many and decrease the severity of the disease in the others. Dr Omar Khorshid, president of the Australian Medical Association, stated on the 15 December 2021, that “We need to urgently reach out to the public and encourage them to come forward for their booster, and GPs are best placed to do this in the population”.
ATAGI has provided advice that the booster:
- be made available to those aged over 18 years
- bring forward the interval between primary course of vaccination and the booster from 5 months to 4 months; as soon as practical offering the booster after 3 months
- Comirnaty (Pfizer) and Spikevac (Moderna-50μg) be offered as the booster. They also recommended that Astra Zeneca be offered for people with contraindications to the Pfizer and Moderna vaccines.
In Australia, boosters are now being offered in Australia to everyone over the age of 18 years, who have received both their primary doses of COVID-19 at least 4 months previously. Earlier booster doses are expected to reduce the risk of symptomatic infection, severe illness and deaths from COVID-19. The aim is to decrease the interval between primary vaccination and a booster dose by 31 January 2022. However, enhanced public health measures such as masks, hand hygiene, social distancing, improved ventilation must also be used.
In the Canberra Press Conference on 9 January 2022 on Omicron, The Hon. Greg Hunt also announced the commencement of the National Children’s Vaccination Program for five-to-11-year-olds beginning on the 10 January 2022.
At a national level on the 12 January 2022, Australia as a community had surpassed 45 million doses (45,076,482 total vaccine doses) including 94.9% first doses. 19,038,946 people were fully vaccinated (92.3% of people over the age of 16 years). 4,363,951 people over the age of 18 had received more than two doses i.e. they had received booster doses.
What is a booster?
The initial vaccine dose prepares and teaches our bodies to make antibodies. The second dose enhances the antibodies so that they better bind to the spike protein. However, as the antibody levels gradually decline, the booster reinvigorates the body’s response and the antibody levels.
How quickly does the effectiveness of the vaccines decline?
In a study which has not yet been published it is suggested that the effectiveness of two shots of Pfizer or AstraZeneca fell to less than 40% of their peak within 15 weeks of the second dose. There was a lesser decline of the effectiveness of the Pfizer against Delta.
The ATAGI statement on the Omicron variant and the timing of COVID-19 booster vaccinations also raised some concern with a recent pre-print study from the UK suggesting that protective effectiveness against symptomatic COVID-19 due to the Omicron strain was not observable after 2 doses of the Astra Zeneca. Further data is being awaited, as the study sample was small. Data from the UK, where booster doses of Astra Zeneca are being administered will help clarify the situation.
As there is a level of concern, individuals who have received Astra Zeneca for their primary vaccinations, should promptly discuss their booster selection with their GP and book to have a booster. The current preferred booster according to ATAGI is a mRNA vaccine (Pfizer or Moderna), should there be no contraindication.
Why does the booster work if there are so many mutations in the spike protein?
The initial vaccines were made to combat the original wild-type SRAS-CoV-2 spike protein first identified in Wuhan. These vaccines have been effective in inducing neutralising antibodies (humoral immunity) and also teaching the cells how to recognise and combat the virus (cellular immunity).
As the effectiveness of the vaccines have waned with time and with the emergence of new variants, the booster doses have been introduced.
These booster vaccines have induced high antibody responses, and it is thought that these induced antibodies may bind more tightly with the variants and help neutralise the virus.
Of more concern, is that in the non-boosted individuals, there may be a low-to-no response against the Omicron variant, demonstrating why the booster is an important element to help your body neutralise the virus.
Whilst there are theories regarding the effectiveness of cellular and innate immunity, at the moment, neutralisation remains the leading form of protection from infection, and this is provided with a booster dose.
Which booster should I get?
A booster vaccine of Pfizer is likely to increase antibody levels by 25-fold, which would be sufficient to neutralise Omicron. Booster doses of Moderna will also improve your body’s ability to neutralise the virus.
Astra Zeneca is not the preferred booster on the ATAGI advice (Version 2 , 24 December 2021). Astra Zeneca may be used as a booster for individuals who have received Astra Zeneca for their first two doses or if there has been a significant reaction to a previous mRNA vaccine, which contraindicates the use of a further mRNA vaccine.
For whom are boosters highly recommended?
- individuals greater than 50 years
- individuals with underlying medical conditions
- residents in aged care and disabilities facilities
- Aboriginal and Torres Strait Islander adults
- individuals at increased occupational risk
- people living in communities with active community transmission of Delta or Omicron variants
Why an mRNA booster?
- Resistance wanes with time: Modelling of medical studies have examined the relationship between neutralising antibody titres and vaccine effectiveness. The investigators predicted that 6 months after primary immunisation with an mRNA vaccine, efficacy against Omicron has decreased to around 40 per cent against symptomatic disease and 80 per cent against severe disease. A booster dose with an mRNA vaccine can increase efficacy against Omicron to 86 per cent against symptomatic infection and 98 per cent against severe infection.
- Astra Zeneca may not protect you against the Omicron variant: It is important to consider that a UK unpublished study has suggested that protective effectiveness against Omicron was not observable after two doses of Astra Zeneca.
- May reduce transmission: This is unclear, however it is thought that reduction in symptomatic disease may also result in a reduction in transmission.
- Reduces severe COVID: According to recent literature in a non-peer-reviewed journal, a booster dose with an mRNA vaccine provides efficacy against Omicron in 86% against symptomatic infection and 98 per cent against severe infection.
- Reduces illness in healthcare system: Boosters will preserve the capacity of the healthcare system to look after you and both your COVID and non-COVID health concerns. As we have recently seen, the healthcare system is facing a crisis due to increasing infection rates and staff furloughing. This furloughing, where staff are sidelined for a period of time to ensure they do not transmit the infection to vulnerable patient populations, means that critical staff available to look after people presenting to hospitals in significantly decreased.
Are there side effects to the boosters ?
The proportion of people having local and systematic side effects is similar to the side effects with the primary immunisation.
The most common side effects were
- local reactions at the injection site with pain
Side effects were more common in people receiving a Moderna booster (compared with Pfizer booster), in those that had a different booster as compared with their primary vaccine and in younger patients. Should you have any concerns please discuss them with your general practitioner.
Is myocarditis still an issue?
Myocarditis is more common after the second dose in younger males. The overall rate for myocarditis is 1.6 per 100,000 doses of Pfizer and 2.5 per 100,000 doses of Moderna.
The preliminary data from Israel on the use of Pfizer as the booster dose suggests that risks of myocarditis with the booster is not increased as compared with the risk after the second dose.
The only reason for ATAGI advising that the interval being brought down gradually from 5 months, to 4 months and then to three months is their concern for the system and the sharp increase in demand for vaccine over the holiday period (on the ATAGI statement on the 24 December 2021).
When will boosters be available to children?
ATAGI is looking at the data internationally. In Chicago amongst other areas, the Public Health Departments support all eligible people age 12 and up to get their booster dose. It is likely that a similar option may be available to children in Australia in the future, in order to minimise missed school and other health issues that occur as a result of COVID-19. It will also serve to protect the more vulnerable elders from the infection.
How do I prepare for Omicron?
According to Professor Michael Kidd, the Deputy Chief Medical Officer, the best thing is to be prepared.
It is likely that many fellow Australians will test positive. Most will have mild disease as they have been vaccinated.
He advised that you have some paracetamol and ibuprofen available for the aches, pains, fevers and other symptoms.
He also advised that you should have fluids at home, including electrolyte solution.
If infected, it is important to drink plenty of fluid to ensuring your body has the best chance of recovery.
As you will not be able to go the supermarket if you are infected, then plan ahead and have the electrolyte solutions, which may be purchased from the pharmacist, available at home.
What do I do if I test positive?
If you have mild symptoms, take the paracetamol or ibuprofen to relieve your symptoms. Keep yourself well hydrated. Get plenty of rest and try to eat well. You may discuss your response with your general practitioner who will be aware of your other medical problems.
If you live in a shared house, isolate yourself, and do not use communal areas. If you need to walk around the house ensure you have an appropriate mask and avoid the others. Use separate cutlery and dishes. Ensure that you do your laundry and wash your dishes at a separate time.
Try to avoid becoming socially isolated. As long as you are not putting others at risk you may try to sit or walk in your garden for short periods of time. Reach out to family via telephone or a web-based service and ensure you discuss your condition and your feelings with your family, friends or colleagues. It is OK to feel anxious and scared. Look after both your physical and mental wellbeing when isolating.
If you require further support with your mental health, you may call your GP, psychologist, psychiatrist, the National Coronavirus Hotline.
If you require advise you may ring the National Coronavirus Hotline on 1800 020 080. This number is available 24 hours a day and seven days a week.
Some other phone lines which may be useful include:
- Emergency Service 000
- Nurse on call on 1300606024
- Lifeline (24-hour crisis counselling) 13 11 14
- Beyond Blue 1300 224 636
- Suicide Line 1300 651 251
If you have a high fever, vomiting, diarrhea, breathlessness or persistent cough and you are feeling fatigued or exhausted then you need to seek medical advice immediately.
If you are unwell and have chest pain, difficulty breathing, then seek urgent assistance and call 000 for an ambulance.
- Garcia-Beltran et al., mRNA-based COVID-19 vaccine boosters induce neutralizing immunity against SARS-CoV-2 Omicron variant, Cell (2022), https://doi.org/10.1016/j.cell.2021.12.033