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Thursday, July 7, 2022
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New vaccine against herpes zoster arrives in Brazil, but only in the private network

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A new vaccine against herpes zoster, also known as shingles, is available in Brazil from this June in private clinics. Called Shingrix and manufactured by the pharmaceutical company GSK, the product has a recommended price of R$ 843 for each dose –the scheme is made for two applications–, but the value may vary depending on the clinic.

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In addition to Shingrix, MSD’s Zostavax vaccine was already marketed in the country. Both can be applied to people over 50 years old, but the GSK product can also be used to people over 18 who are immunosuppressed – people with HIV or undergoing cancer treatment, for example.

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Immunizing agents are indicated for these groups because they are at greater risk of developing the disease. The condition is caused by the varicella-zoster virus, the same virus that causes chickenpox, which remains latent throughout the life of the infected individual. When it is reactivated, usually in the elderly or with compromised immune system, the person can develop shingles, which in rare cases can cause death.

According to the CDC (Centers for Disease Control of the United States), 1 in 3 people in the North American country can develop the disease. The risks increase the older the person is. In the MSD vaccine package insert, it is mentioned that in those over 85 years of age the health problem is expected in 1 in 2 individuals. In the Covid-19 pandemic, cases of the disease also increased.

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The main symptom of shingles is skin lesions. Lauro Pinto Neto, a physician and member of the Technical Committee for Review of Vaccination Schedules at Sbim (Brazilian Society of Immunizations), says they have some similarities to the wounds seen in monkeypox cases, because they also cause blisters and pustules.

“The difference with herpes zoster is that they are more localized lesions, they do not spread throughout the body”, he says.

After this acute phase, the person may heal completely or present some complications, the main one being post-herpetic neuralgia. This problem causes a chronic pain, itching, and burning sensation that lasts for months or years.

As a long-term condition, post-herpetic neuralgia requires a long and expensive treatment with anticonvulsant medications. “These are medications that act on the nerve ending”, explains Pinto Neto. In addition to them, antidepressants and potent analgesics, such as opioids, can be adopted.

Even so, the current treatment is not effective in all patients, says Thiago Cunha, professor at the Department of Pharmacology at the Faculty of Medicine of Ribeirão Preto (FMRP) at USP (University of São Paulo).

“And in those who answer [aos medicamentos]there is a very small improvement”, he adds.

Cunha is already researching how to prevent post-herpetic neuralgia from developing in patients with herpes zoster. He explains that the ideal is to reduce the acute phase of the disease, as this reduces the chances of the onset of chronic pain.

One of the ways for this can be TNF (Tumor Necrosis Factor), which is an inflammatory mediator. In a mouse study with HSV-1 – which is the herpes simplex virus and the same family as varicella-zoster – blocking TNF during the acute phase had an impact on preventing chronic pain.

“The TNF participates in some way, which we still don’t understand so well, in this chronification process”, says Cunha.

However, there is a dilemma. As an inflammatory mediator, TNF also plays a role in controlling viral infection. “When inflammatory mediators are used, in some circumstances, the response against infection is impaired”, explains the professor. Even so, it was seen that animals treated with anti-TNF medications were able to deal with the infection, but it took a little longer.

The idea is that the adoption of a pharmacological regimen with TNF inhibitors and anti-virals may be ideal to avoid post-herpetic neuralgia. This still needs more research, not least because a virus from the same family as varicella-zoster was used, but without being the pathogen itself, since it does not infect mice.

Vaccines still unavailable in the public network

One way to prevent the onset of the disease and its complications is through the two herpes zoster vaccines. In Brazil, immunizers are still available only in the private network.

“Every discussion of vaccine in the public network involves the issue of cost-benefit”, says Pinto Neto. The doctor also says that other vaccines may have a higher priority for incorporation into the SUS before immunizations for herpes zoster. One example is the definitive inclusion of vaccines against Covid-19 in the vaccination schedule.

For Thiago Cunha, it is important to consider, in the evaluation of incorporating the immunizing agent into the SUS, that the disease can greatly affect the patient’s quality of life.

“The individual has very intense pain. He can barely put on clothes or take a shower. This lasts for months or years in which the person has a great loss in quality of life”, he says, referring to post-herpetic neuralgia.

An example of a public health system that adopted vaccines for herpes zoster was the NHS (National Health System), a kind of SUS in England. Immunizations are available for people aged 70 to 79 years. Both the MSD and GSK vaccines are administered by the agency.

Currently, the national vaccination schedule has the tetraviral vaccine that prevents chickenpox (chickenpox) and is applied to children. Because they are caused by the same virus, it may be that this immunizing agent will reduce cases of herpes zoster in the future, but this lacks scientific evidence.

“This generation vaccinated for chickenpox, in the future when they reach 50 or 60 years, may have less herpes zoster, but it will not be zero”, says Pinto Neto.

THE Sheet contacted the Ministry of Health for comment, but received no response as of the publication of this report.

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