Covid: Can you get infected again and do BA.4 and BA.5 have different symptoms?

According to the Office of National Statistics (ONS), more than 1.7 million people are currently infected in the UK – a 23 percent increase from last week.

The rise in cases has been driven by two sub-variants of the original Omicron strain that triggered the country’s fourth wave last December.

With large segments of the population already contracting the virus during the pandemic, reinfections have become more common – especially since the arrival of Omicron.

The emergence of five other sub-variants of Omicron has further complicated the picture, with BA.4 and BA.5 now supplanting the previously dominant BA.2 strain.

According to the latest analysis from the UK Health Security Agency (UKHSA), BA.4 is growing about 19.1 percent faster than BA.2, while BA.5 is growing 35.1 percent faster. And each time the virus mutates, the chance of reinfection increases.

Fortunately, the number of fatalities has remained low compared to the rising infections. Hospital admissions have increased, but remain well below the original Omicron peak over Christmas.

But how likely is a reinfection, what are the main symptoms of BA.4 and BA.5 and how much protection do vaccines offer against reinfection over time?

How common are reinfections?

According to ONS data, the number of reinfections increased 15-fold after the arrival of Omicron in December last year.

This is partly due to Omicron’s extensive mutations, which allow it to evade the immunity conferred by previous infection. It could explain why so many people who had been vaccinated or previously infected caught the virus again over the Christmas period.

Both BA.4 and BA.5 have now been shown to evade immunity from a native Omicron infection, according to experts.

“The original Omicron BA.1 variant was itself hugely immune-evasive, causing a huge breakthrough even among the vaccinated,” Danny Altmann, a professor of immunology at Imperial College London, told The Guardian.

“It is also poorly immunogenic, so trapping it offers little additional protection against re-capture. In addition, there is now further evidence of past Omicron’s very marginal ability to prime any immune memory for BA.4 or 5, the subvariants that appear to be driving the latest wave of infections.”

Early data on reinfections related to the new subvariants seem to support Prof. Altmann’s claim.

Harvard Medical School researchers found that both BA.4 and BA.5 seemed to escape antibody responses in those who had had a previous Covid infection and those who had been vaccinated three times.

dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Harvard’s Beth Israel Deaconess Medical Center, told CNN, “Our data suggest that these new Omicron subvariants are likely to lead to an increase in infections in populations with high levels of vaccine immunity as well as natural BA.1 and BA.2 immunity.

“However, it is likely that vaccine immunity will still provide substantial protection against serious diseases with BA.4 and BA.5.”

Do Omicron and BA.4 and BA.5 have different symptoms?

Omicron itself marked a shift in symptoms from earlier variants, including Delta and the original Wuhan strain.

A study by Kings College London and the ZOE Covid app, published last April, found that the most consistent symptoms in Omicron were a sore throat, hoarse voice and headache.

Researchers also found that some of the more debilitating symptoms, such as brain fog, eye burning, dizziness and fever, were significantly less common in Omicron cases.

According to early research from the UK Health Security Agency (UKHSA), there is currently “no evidence” to suggest that BA.4 and BA.5 cause more serious illness than previous variants.

It’s unclear whether BA.4 and BA.5 cause different symptoms, but scientists haven’t noticed any changes yet.

Will my symptoms be milder if I’m re-infected?

In general, Covid gradually becomes milder in patients due to the immunity developed from previous infections.

However, scientists have noted that the two new subvariants can evolve to target lung cells, bringing them closer to the more severe Alpha and Delta variants.

dr. Stephen Griffin, a virologist at the University of Leeds, said: “It looks like these things are switching back to the more dangerous form of infection, so lower in the lungs.”

What difference does vaccination make?

Because Omicron is constantly evolving, scientists have warned that the current batch of vaccines used around the world may need an update, even if they continue to provide good protection against serious diseases.

Meagan Deming, a virologist and vaccine scientist at the University of Maryland School of Medicine in Baltimore, told Nature she believes it’s time for new shots to counter new subvariants.

“The virus is changing and what worked two years ago may not work for future variants,” she added.

There is no specific date on the efficacy of vaccines against the BA.4 and BA.5 strains. However, protection against BA.2 rose to about 70 percent four weeks after a third vaccine dose, according to government data published in March.