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Health Expert Answers Common Questions About The Omicron Variant

As part of a Q+A session with ANZ New Zealand staff, Australian public health physician Dr Natalie Gray provided an update on the Omicron variant, and answered questions on issues like vaccinations and the use of masks.


How does Omicron differ from previous variants?


Omicron was first detected in a sample in November 2021 and the World Health Organisation quickly identified it as a variant of concern. That’s because it has a large numbr of mutations, some of which allow it to enter the body’s cells more easily, impair your immune response and allow Omicron to be transmitted more easily.


In plain language: it is more infectious.


Some key factors about Omicron have become apparent over the past couple of months, which help determine the best ways to control it.



Omicron is transmitted through airborne transmission


You get it by breathing in the air that someone else has breathed out when they have Omicron. When someone is infected with Omicron they can transmit it by coughing, breathing, sneezing or even speaking. 


The virus particles stay in the air, either in droplets (which are bigger particles that stay in the air for a short time and then fall to the ground) or aerosols (which are very small particles that stay in the air).


One study has found that tha virus remains infectious in the air for about 20 minutes. So after the 20 minute mark its ability to infect you drops by about 90%.


It’s appears Omicron spread most often via these airborne droplets, as opposed to getting it by touching a doorknob that someone with Omicron has touched and then touching your face, for example.


Another major difference is that Omicron targets people’s uppers airways, rather than their lungs.


With Delta it targeted the lungs, with serious cases getting lung infections, or pneumonia. Pneumonia is a serious illness which can lead to hospitalisation, intensive care and in some cases can be fatal. The symptoms of Delta lung infections include fevers, a persistent cough, shortness of breath or chest pains.


In contrast Omicron is generally found in the upper airways, in the back of the nose and in the throat.


The symptoms of Omicron appear to be more like a cold with on of the most common symptom being a runny nose. One UK-based reseracher has found that almost three quarters, 73% of infected people, will have a runny nose.


About 68% will have a headache. Fatigue is also prominent, as is sneezing or a sore throat.


The common symptoms of Delta (such as a cough, fever, altered smell and taste, chest pains) can happen, but are much less common.


Symptoms that present as a cold tend to be less serious medically than symptoms that present as a lung infection or lower respiratory tract infection. That is why hospitalisation rates for serious illness are lower for Omicron then we saw for Delta.


How does Omicron affect children?


Small children, especially under five, have very reactive airways, and if they get an upper respiratory tract infection can get croup (croup is when they wake in the night with a barking cough, or they have difficulty breathing).


So Omicron can cause croup. This has seen an increase in the hospitalisation of children compared to previous variants. But it is treatable with steroids. So it is important that parents are aware of the risk of croup and seek medical care if they are concerned.


Although the virus prefers upper airways, some people (especially the elderly and immuno-supressed) can still get serious respiratory illnesses. There will be some people who will get very unwell from Omicron.


"It's important to reduce the Omicron wave so that it does not overwhelm the hospital system. The overwhelming of the hospital system means people missing elective surgery, missing cancer screenings, and so on. ."
- Dr Natalie Gray, Public Health Physician.



What happens when you are vaccinated?


When you are vaccinated two things happen.


You produce antibodies, which stop the spike protein from attaching to the receptors in your body, helping prevent infection.


At the same time a vaccinated person produces T-cells that can kill cells infected by the virus, reducing the length and severity of an Omicron infection.


So the antibodies can stop you getting infected and the T-cells can stop you becoming seriously ill.


Why is the booster so important?


When we look at Omicron we see the antibody levels drop quickly after the second vaccination.


Six months after your second dose (irrespective of vaccine manufacturer) you will have very limited protection against infection.


That’s because our antibody levels have dropped and the virus has mutated to evade antibodies.


The good news is that T cell levels appear to remain strong, providing strong protection against hospitalisation and mortality.


But we still want to try to slow community transmission so everyone is not getting infected. That’s because even though hospitalisation rates are lower with Omicron, if high numbers are getting infected, even a small percentage of people being hospitalised could overwhelm hospital systems.


What we know about the third dose (whether it’s Pfizer or Moderna) is that it raises antibody levels much more quickly. In the first three months after the booster, antibody levels go up to provide strong against symptomatic infection. T-cell levels go up as well, providing strong protection against serious illness or hospitalisation.


At around the 4 to 6 month mark the antibody levels start to wane again, lowering our protection to symptomatic infection. This is something that is commonly seen with viruses, and raises the possibility that we may need more boosters into the future.


However, what we most want to do is prevent hospitalisations and fatalities. What we know is that the best way to get through an Omicron wave is for people to get the third dose booster as soon as they are eligible.


Children don’t generally get as sick as adults do from Omicron, why then is it important for them to be vaccinated?


There are four major reasons for getting children (aged five to eleven) vaccinated.


1.    It reduces Covid in that age group. For children aged 5 to 11, trial results showed the Pfizer vaccine was 90.7% effective against getting COVID-19 symptoms, and what was amazing was that none of those who got the jab developed severe COVID-19. So vaccinating kids during the Omicron wave will help reduce overall hospitalisation rates.


2.    It reduces long Covid. From UK data we have seen that around 10% of kids aged 2 to 11 have at least one debilitating symptom five weeks after getting Covid.  Often these symptoms relate to 'brain fog' which includes difficulty concentrating and headaches. These can persist at least as long as 12 weeks and can impact children in many ways including disrupting their learning. Vaccination is effective at reducing long Covid.


3.    Anything that reduces community spread will help make the duration of the wave shorter. We want to see as few people as possible infected, and for the peak and duration of the Omicron wave to be as low as possible.


4.    Vaccinating children lowers outbreaks in schools. We know face to face learning is really important, so outbreaks can be very disruptive. So to curtail outbreaks in schools the easiest way to do that is to increase vaccination rates amongst 5 – 11 year olds.


More from the NZ Ministry of Health on vaccinating children.


What do we know about the vaccines’ side effects?


With the mRNA Covid vaccines there are three points of time when you can have a side effect:


1.    Immediately after being vaccinated, as some people will be allergic and have an anaphylactic reaction. This is the same with all medications and there are ways to manage this.


2.    The second point of time is within the first 72 hours, when your immune system is reacting very strongly. That’s when you get headaches, or a fever, or feel generally unpleasant. This is the case with all vaccines, both traditional and mRNA vaccines. It’s a sign your immune system is working properly.


3.    The third period is the following six to eight weeks. That’s when your immune system is coming back to normal and you can have a rare side effect that is the same as the side effects from Covid itself. Myocarditis is an example – the inflammation of the heart wall. It’s a result of the immune system overreacting to the vaccine. The side effects are not random and are related to Covid-19.


There is no evidence of any side effects after eight weeks. There are very strong systems in place to monitor people’s potential reactions to the vaccine well into the future. Anyone who thinks they have had a reaction should report it and it will be investigated.




There has been a lot of talk about masks and the effectiveness – what do I need know?


After vaccination, the next most effective thing to combat Omicron is to wear a good mask.


If everyone is wearing a mask and someone is infectious, it means the virus from them does not get into air as effectively. That means those around them are less likely to breathe in the particles from the air. If we are socially distanced the virus particles are less likely to travel from the person who is infected to you.


There is evidence the better masks, like N-95 or P-2 masks, are more efficient at filtering the large particles and small aerosols. But the N-95 and P-2 masks are more difficult to wear and can be uncomfortable over longer periods.


The other things is that to be effective they need to be fitted correctly. So the best mask is the one you are using consistently and correctly. If you remove it to eat, ideally you’d put on a new mask.


N-95 masks are good for high risk situations such as visiting an elderly person in a rest home, or visiting a hospital. Otherwise just look at using surgical or three layered cloth masks.


How likely is it to contract Covid in an office setting?


This depends on the number of cases in a day. If case numbers are low the risk is lower, but at Omicron’s peak the risk will be much higher.


It’s estimated that for every positive person in a household the risk of transmission is 39%. The risk in a workplace is lower, if people are triple vaccinated, wear a mask and are socially distanced. Provided that people do not come to work if they have symptoms (runny nose, cough, fever, etc).


What’s the difference between PCR (Polymerase Chain Reaction) tests and RAT (Rapid Antigen Tests)?


PCR are the gold standard. They will tell you if you have Covid-19. PCR tests detect infection during the early, middle and later stages of infection.


RAT tests can deliver a result very quickly (around 20 minutes). But they have a smaller window to detect if someone is infected. They will tend to detect Covid when someone is at their most infectious or symptomatic.  The sensitivity and accuracy can vary from one manufacturer to another.



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