Chickenpox is a disease that has accompanied the history of humanity and occurs in practically all people in childhood or adolescence.
The problem is that the virus remains “asleep” in the body’s nerve cells and reactivates in one in three individuals, starting at the age of 50, as herpes zoster (HZ) with its main complication: postherpetic neuralgia: intense pain generated in the nerve cells that can last several months, stated Édgar Pérez Barragán, Project Director of the Society for Research and Teaching in Virology and Infectology (Sidvi).
He pointed out that the greatest risk of HZ is those who have a weakened defense system due to some other condition, such as cancer, diabetes or an autoimmune type.
It was only a couple of decades ago that the first HZ vaccine was developed, with an efficacy of 50 percent in preventing infection and 70 to 75 percent effective in preventing postherpetic neuralgia.
In 2017, the United States Food and Drug Administration (FDA) approved the second recombinant HZ vaccine, produced through genetic engineering and with an effectiveness of more than 90 percent in preventing the disease and 95 percent against neurological pain.
In Mexico it began to be used in 2023, but the majority of the population is unaware of its existence, in addition to the fact that it is only available in the private sector, commented the specialist.
In an interview, he said that the varicella zoster virus is very stable, it practically does not change in its structure. In children it causes a highly contagious disease, but due to its characteristics, it has been seen as normal, since the discomfort (fever, blisters and itching) disappears in a couple of weeks and the children return to their normal activities.
Furthermore, since the 1990s, a biological product has been available that offers high protection against chickenpox. Although it is not included in the universal vaccination scheme, it is a mandatory requirement for children who attend daycare centers and is applied by social security institutions.
The challenge for health systems is the ability of the virus to remain “asleep” for decades, and when it “awakens” in adulthood as herpes zoster, it disrupts the quality of life and productivity of those affected. And blisters also appear on the skin, with intense pain and itching, and leave scars. Furthermore, there is a high probability of recurrence.
Pérez Barragán explained that the chickenpox virus lodges in the nerve ganglia and when it is reactivated it causes inflammation, hurts and kills nerve cells. That’s what causes postherpetic neuralgia, with pain and burning, usually on one side of the head. Those affected by HZ lose sensitivity and strength.
The symptoms tend to be more severe in older adults who live with other illnesses, such as diabetes, especially if they already have diabetic neuropathy, kidney or lung failure.
In these cases, the probability of health recovery decreases. Hence the importance of preventing HZ with the application of two doses of the recombinant vaccine.
Pérez Barragán also highlighted that the effectiveness, quality and safety of the biological was proven a decade ago in a randomized clinical trial in which people from different countries participated, including around a thousand Mexicans. So there is evidence about the effectiveness of the product, he said.
