Scientists develop an HIV vaccine that showed almost 100% effectiveness against the virus

The global medical community is increasingly calling lenacapavir (Lenacapavir) one of the most significant achievements in HIV treatment and prevention in recent decades. After the publication of the results of large-scale clinical trials, the drug demonstrated almost 100% effectiveness in preventing infection with the human immunodeficiency virus, and the World Health Organization recommended it as a new option for pre-exposure prophylaxis (PrEP).

But what makes this drug so special, and has humanity really come closer to defeating HIV?

What is lenacapavir

Lenacapavir is a drug developed by the American company Gilead Sciences. It belongs to a completely new class of antiviral agents — HIV capsid inhibitors.

Before its introduction, virtually all modern medicines targeted viral enzymes — reverse transcriptase, protease or integrase. Lenacapavir is the first to attack a different structure — the capsid, the protein оболочка of the viral particle.

It is the capsid that protects the virus's genetic material and plays a key role in virtually every stage of the HIV life cycle.

How the virus infects the body

To understand how the drug works, it is important to understand how the virus itself functions.

After HIV enters the body, several consecutive stages take place:

1. the virus attaches to an immune cell (usually a CD4 T lymphocyte);

2. it enters the cell;

3. it releases its RNA;

4. it converts it into DNA;

5. it inserts this DNA into the human genome;

6. it begins producing thousands of new viral particles;

7. the new viruses leave the cell and infect others.

Most existing drugs block only one specific stage.

Lenacapavir acts much more broadly.

How lenacapavir works

The capsid is a kind of «container» that holds the virus's genetic material.

Lenacapavir binds to capsid proteins and disrupts several processes at once:

the virus cannot properly uncoat after entering the cell;

the transport of viral DNA to the cell nucleus is disrupted;

the integration of the virus into human DNA becomes more difficult;

new viral particles are assembled incorrectly and become non-viable.

In effect, the drug strikes several stages of the virus's life cycle at once.

This is why specialists consider its mechanism of action revolutionary.

Why only two injections a year are needed

Lenacapavir's main feature is its remarkably long-lasting effect.

The drug is administered subcutaneously.

After the injection, it is released slowly from the tissues and maintains a therapeutic concentration for approximately six months.

That is why a person needs only two injections a year.

For comparison:

traditional PrEP requires taking pills every day;

some modern drugs are administered once a month or once every two months;

lenacapavir works for about six months.

This significantly reduces the risk of missing a dose — one of the main reasons for reduced prevention effectiveness.

Why this matters

According to UN estimates, around 1.3 million new HIV infections occur worldwide every year.

The main problem with existing prevention is not the medicines themselves.

It is people.

Taking pills every day for many years is difficult.

People forget, stop treatment, move, or lose access to medicines.

Just two injections a year could virtually eliminate this problem.

What the studies showed

The international PURPOSE 1 and PURPOSE 2 studies attracted the most attention.

Thousands of volunteers from different countries took part in them.

The results were so convincing that specialists called them historic.

In the group receiving lenacapavir every six months, new infections were virtually absent.

The drug proved more effective than the traditional regimen of daily preventive pills.

It was following the publication of these data that the WHO included the drug in its recommendations.

Is this a vaccine?

No.

This is one of the most common misconceptions.

Lenacapavir is not a vaccine.

A vaccine trains the immune system to recognize the virus in advance.

Lenacapavir does not affect the immune system in any way.

It simply creates a constant concentration of medicine in the body that blocks the virus immediately after it enters.

As long as the drug is present in the blood, the virus cannot fully initiate the infectious process.

Can the drug completely cure HIV?

Not yet.

If a person is already infected, the virus manages to integrate into the DNA of some cells in the body.

These hidden reservoirs remain the main reason a complete cure is impossible.

Lenacapavir can:

effectively treat the infection as part of combination therapy;

prevent infection in healthy people.

But modern medicine is still unable to completely remove the virus from the body.

Side effects

According to the study results, the drug is generally well tolerated.

The most common side effects were:

redness at the injection site;

soreness;

slight swelling;

headache;

mild nausea.

Serious complications were rare.

Why the drug has sparked a scandal

Despite the scientific breakthrough, access to the drug remains extremely limited.

In the United States, the cost of a year's treatment is around 28,000 dollars.

At the same time, independent studies show that the cost of production may be tens or even hundreds of times lower.

Gilead has authorized the production of low-cost generics for a number of the poorest countries, but many middle-income countries — including Brazil, Mexico, Peru and Argentina — were not included in the licensing program.

That is why, at the International AIDS Conference in Rio de Janeiro, the drug became the subject of heated debate between governments, civil society organizations and the manufacturer.

Why this could change the history of medicine

Experts believe that the significance of lenacapavir goes far beyond the arrival of yet another medicine.

For the first time, HIV prevention is becoming as simple as possible: two injections a year instead of taking pills every day. If the drug becomes available at an affordable price, it could significantly reduce the number of new infections, especially in regions where the virus is widespread.

At the same time, it is important to understand that lenacapavir is not a vaccine or a definitive cure for HIV, but a highly effective means of prevention and a component of therapy. Nevertheless, many specialists call it the most serious breakthrough in the fight against HIV since the emergence of modern antiretroviral therapy in the 1990s. The main question is no longer whether the drug works, but whether millions of people around the world will be able to access it.