Over 50? Time to consider a shingles vaccine

IT has long been suspected that COVID-19 is associated with a higher risk of developing herpes zoster (shingles) in adults aged over 50 years. With increasing research confirming case reports and theories, experts are urging older Australians to stay up to date with their immunisations.

Herpes zoster is caused by a herpesvirus (varicella zoster virus), the same virus can manifest as chicken pox when you are infected for the first time.

According to Charles Sturt University molecular virologist Dr Brian McSharry, the virus can remain latent in neurons for decades.

“Shingles is caused by the reactivation of this virus that previously caused chickenpox, thought to be due to reduced immunity in older people,” he explained.

Higher risk of shingles from acute COVID-19

Earlier in 2022, the retrospective cohort EPI-ZOSTER-090 study, published in Open Forum Infectious Diseases, measured the risk of developing shingles in people with COVID-19.

The authors examined a total of 394 677 people in the US aged 50 years and over who had been diagnosed with COVID-19 and compared them with 1 577 346 individuals who hadn’t had COVID-19. They found that individuals diagnosed with COVID-19 had a 15% higher herpes zoster risk than those without COVID-19. People who had been hospitalised following their SARS-CoV-2 infection faced a 21% increased risk of developing shingles.

UNSW Sydney School of Population Health Associate Professor Anita Heywood told InSight+ that the study results are “definitely plausible”.

“Life events, such as episodes of immunosuppressive treatments, can lower your immune system and are known to increase the risk of zoster,” she said.

According to the study authors: “The elevated HZ [herpes zoster] risk in these populations is thought to be a consequence of a decline in VZV [varicella zoster virus]-specific cell-mediated immunity below a threshold required to maintain latency of the virus”.

Risk factors for herpes zoster

However, Associate Professor Heywood highlighted that the study matched for a range of risk factors for herpes zoster.

“It’s not just the general 50 years and over population. It’s people 50 and over who are already at increased risk of zoster, both those with COVID-19 and those without,” she said.

“Twenty per cent of those included in the study had an immune-compromising condition. And that’s a huge risk factor for zoster. So they’re already at higher risk.

“Fifty-eight per cent of the COVID-19 and 56% of the non-COVID-19 patients had another risk factor as well,” she highlighted.

“Things like rheumatoid arthritis are risk factors because patients are on such strong immunosuppressive medications that increase their risk.

“It’s a good study. They’ve used really good data and they’ve done a good analysis. But I don’t think the impact is huge. Absolute differences between COVID-19 and non-COVID-19 patients was an additional 1.4 cases of zoster per 1000 person years, from 6.81 to 8.16 cases in non-COVID-19 and COVID-19 groups,” she said.

There are other risk factors for zoster that people should be aware of.

“There’s a lot of data out there showing huge increased risk after chemotherapy, or when you’re on immunosuppressants, like if you’ve had an organ transplant. Age is a big risk factor. And I think, even things like depression, which tries to lower your immune response,” Associate Professor Heywood explained.

Is there a shingles risk from the mRNA vaccines?

There have been sporadic case reports of development of shingles after COVID-19 vaccination, but according to Dr McSharry, a study has refuted that.

“A study of more than 1 000 000 individuals who had been vaccinated showed no increased risk of shingles compared with controls, so most likely there is no specific link,” he explained.

“Our data suggest mRNA COVID-19 vaccination is not associated with increased rates of VZV reactivation. We hope this reassures patients and the providers caring for them,” the study authors wrote.

Is there a long COVID link to herpes zoster?

According to the EPI-ZOSTER-090 study, the shingles risk declined after 6 months post-infection.

“In the published case reports and case series, more than half of the described [herpes zoster] cases occurred within 1 week after COVID-19 diagnosis or hospitalisation, but some cases were also reported after 8–10 weeks. This is consistent with the results of the present study, in which an increased risk was observed up to 6 months after COVID-19 diagnosis. No increased risk of developing [herpes zoster] was seen beyond 6 months after COVID-19 diagnosis in our study, which may indicate a recovery of cell-mediated immunity,” the authors wrote.

However, a non-peer reviewed preprint paper from the Department of Immunobiology at Yale School of Medicine found that study participants with long COVID had elevated levels of antibody responses to herpes viruses.

“REAP (Rapid Extracellular Antigen Profiling) detected elevation in IgG against herpesvirus antigens. In particular, antibody reactivity to glycoproteins and early antigens of Epstein–Barr virus [EBV], varicella zoster virus were elevated in long COVID over other groups,” author Professor Akiki Iwasaki wrote on Twitter.

“The increases in antibodies to EBV and VZV antigens were also detected using independent assays like ELISA and Serimmune epitope mapping. However, seroprevalence for EBV and VZV were similar in long COVID and convalescent controls. These data suggest recent reactivation of EBV and VZV in long COVID,” she continued.

Highlighting the importance of vaccination

The EPI-ZOSTER-090 study was supported by GlaxoSmithKline Biologicals SA. In 2021, GSK released Shingrix, a new shingles vaccine that has been approved for people aged 50 years and older in Australia and is available on the private market.

Australia’s current national immunisation program provides the Zostavax vaccine (Merck Sharp and Dohme) at age 70 years and there is also a catch-up program for people aged 71–79 years. This program has been extended until the end of October 2023.

A shingles vaccine is also recommended for people aged 60 years and over, and adults 50 years and over who live with someone who is immunocompromised.

According to Associate Professor Heywood, it is a good time for a reminder about the risks of herpes zoster and the need to get vaccinated.

“The vaccine uptake has been really slow, partly because it took a long time to get on to the program and there were some supply issues.

“It’s a call for people who are over 50 years, who might be at risk of zoster, to consider getting a vaccine. It could be COVID-19, it could be other risk factors that increase their risk, and that can be reduced by getting a vaccine,” she concluded.

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