Covid-19 symptoms: How do I know if I have Omicron or Delta?

Loss of taste is often not a feature of Omicron, but headache and cold symptoms are


How do Omicron symptoms differ from earlier Covid-19 variants such as Delta and Alpha?

GP and associate clinical professor of general practice, Dr Ray Walley says that he hasn’t seen any patients recently who have lost their sense of taste or smell. “Headache and head cold symptoms are the most prominent symptoms with Omicron but I have seen some gastrointestinal symptoms in children and in the elderly,” says Walley.

Infectious disease consultant at Beaumont Hospital Dr Eoghan de Barra adds that many people with Omicron have “headaches, runny noses and low energy without chest pains or oxygen requirements of previous infections” – although he has seen older patients with loss of appetite and constipation, as well as unvaccinated patients with severe infection presenting with low levels of oxygen and diffuse pneumonia symptoms.

De Barra cautions attribution of symptoms to Omicron alone. “Infection depends on the host [human] as well as the pathogen [in this case the Covid-19 virus], so with over 90 per cent of the population vaccinated and others who have had infections with previous variants, we can’t rule out that our bodies are reacting differently to the virus rather than the virus itself being different.”

Can I catch both Omicron and Delta or be sick from one variant after the other?

Walley says that he is not aware of anybody getting both Delta and Omicron at the same time. “I have had patients – including some who have been vaccinated and boosted – who had Covid in early December and were positive on antigen tests again in January, which means they have had both Delta and Omicron.”

Will the antibodies I develop after being sick protect me against catching new strains of Covid-19?

It’s impossible to say for sure. Antibodies from infection with or vaccination against Covid-19 will reduce the severity of future infections, although as long as large sections of populations in the developing world remain unvaccinated, new more dangerous variants can still emerge. That said, a recent study in South Africa found that an Omicron infection somewhat protects against future Delta infections.

With one million cases of Covid-19 now detected in Ireland (and many more undetected), can we now say the disease is endemic?

US infectious disease expert, Dr Anthony Fauci has said that he doesn’t see the threat of Covid-19 remaining as it is. “Even with viruses that mutate and change, you reach a steady state where there’s enough infection and/or vaccination in the community that there is enough background immunity that the level of infection is both less in quantity and severity of disease,” said Fauci.

Because Omicron is predicted to infect about 40 per cent of the global population in the next two months, it is expected to raise population immunity for a while. However, endemicity relates specifically to each variant in each region, and the arrival of a new more severe variant from abroad always remains a threat.

“The problem is if we play down this wave too much, there may be other waves in which the host/pathogen interaction is different because the virus is changing but so are the humans,” says de Barra.

Do we need to continue to be fearful of Covid or in future will only vulnerable individuals need boosters and protective measures?

Walley believes that it’s too early to let down our guard. “We are still one to two weeks away from seeing whether there will be an increase in admissions to intensive care units from the Omicron wave. I’m cautiously optimistic but we need to remain vigilant, and it’s time now for people who are immune-compromised to get their fourth vaccine dose, as their third dose was almost three months ago, and the effectiveness of the vaccine will have waned by now.”

According to Walley, this Omicron wave doesn’t appear to be as serious for the vaccinated but it is serious for those who aren’t vaccinated and those who are immuno-compromised. “The greatest majority of people who are getting sick are unvaccinated,” he adds.