Coronavirus: After exposure to Omicron BA.4 and BA.5, how long does it take for COVID symptoms to appear?

COVID-19 in 2020 versus COVID-19 in 2022 are like two sides of the same coin. While they're still the same virus, they may differ in terms of symptoms, severity and long term complications. Variants like the alpha, beta and the delta took a severe toll on our health and raised our risk of other health conditions. But its successor - the Omicron - although more transmissible, seems to cause milder infections. Additionally, the new subvariants of the Omicron namely BA.4 and BA.5 have also become dominant in many parts of the world, including the United States of America.

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Omicron subvariants BA.4 and BA.5 were first detected in South Africa in January and February 2022, respectively. These are the newest version of the Omicron and currently the most dominant. Currently, they account for about 80% of COVID-19 cases in the U.S.

The World Health Organization (WHO) recently said that BA.5 now accounts for more than half of the world’s cases, while BA.4 accounts for just over one in 10. They're said to be the most transmissible and immune-evasive variants of COVID-19, but are more likely to cause milder infections, as per experts.

Regarding the BA.4 and BA.5 Omicron subvariant, another aspect that has come to the fore are its incubation period. How long does it take for the symptoms to appear after an exposure to the new sub variants?

During a Facebook live, Dr. Allison Arwady, Chicago Department of Public Health Commissioner, stated that recent studies have shown that the incubation period for COVID-19 has shortened with newer variants on the rise.

So if you go back to the alpha variant, beta, delta - early on, it was about a five-day incubation period on average. So, if you were exposed to COVID, on average we were seeing people take about five days for someone to end up testing positive - and remember that went from four to five, out to 10, out to 14," she said.

"The reason ... we only use 10 days now, it is because that timing has shortened. And so, more recently with BA.4, BA.5, that's all the way down to about three days now. So on average, people are testing positive about 3 days after, but you can have someone positive up to 10 days," the expert adds.

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The study, published in the journal JAMA Network Open, looked at and analysed 141 studies to find out how COVID's incubation window, which is the time from when you get infected to when you start showing symptoms, has altered since early 2020.

The researchers from Beijing found that with every new variant, the incubation period decreased considerably. The Omicron variant is said to have the shortest time frame between an infection and the onset of symptoms.

“The incubation periods of COVID-19 caused by the Alpha, Beta, Delta and Omicron variants were 5.00, 4.50, 4.41, and 3.42 days, respectively,” the researchers said.

However, given that much of the study relied on the participant's memory of when they were infected and when they showed symptoms, there is still some ongoing speculation.

Dr Arwady believes it as 'excellent news'. She says, "That is excellent news from a control perspective and because one of the biggest challenges of COVID is that... when the incubation period is long, you can get infected with COVID, potentially a long time before you have significant symptoms and it'll be spreading it."

"So it's good news to see that incubation period getting shorter," she adds.

However, according to the WHO guidelines, the incubation period for COVID-19 remains to be on average 5-6 days, which can go up to 14 days.

Taking to Zoe’s (COVID symptoms study app) YouTube channel, Prof. Tim Spector recently shared the “latest” Covid signs."

“[They] seem to have changed a little bit now that Omicron BA.5 is really dominant in the UK," he said.

“It's looking like it's causing fewer symptoms and maybe milder in most people. Of course, there are exceptions and some people are still getting very severe diseases.

“It's possible that BA.5 causes symptoms with a lower amount of virus and that could explain the slightly milder symptoms.

“Anyway, sore throat is still the predominant symptom here, followed by headache.” The next two signs were blocked nose and cough without phlegm, seen across 48 and 46 percent of respondents respectively," he adds.

Other symptoms according to data are a runny nose, hoarse voice, sneezing, fatigue, muscle pain and dizziness.

Being aware of the symptoms, isolating when these symptoms appear are a great way to curb the spread of COVID-19. Furthermore, you can wear your masks, maintain social distance and follow proper hand hygiene.

Most importantly, get your vaccines or booster shots as soon as possible. While these do not give your complete immunity, it can prevent severe illness and complications.