Introduction

Monkeypox is not a rare disease or isolated syndrome affecting specific African regions anymore. During 2024, global attention was shifted towards a new strain of monkeypox regarding its high transmission spread and its appearance in different countries worldwide. The fast spread of the monkeypox raised flags about the effectiveness of the current vaccines and whether they still offer the same protection efficiency as the similar previous pox diseases.

This article will explain how this mutant strain of monkeypox in 2024 has impacted the efficiency of the existing vaccines and whether new strategies will be adopted by the WHO and other medical regulatory parties worldwide to contain this virus. 

What is monkeypox?

Monkeypox is a rare viral infectious disease. Poxvirus and its other DNA virus groups are the cause of the monkeypox disease, among other diseases that are considered life-threatening. threatening to human health as the smallpox virus (which was known to be eradicated in 1980) cowpox. It was primarily discovered in a research center in Copenhagen, Denmark, in 1958 in an infected Asian monkey. Before May 2022, the disease was localized in central and west African countries (endemic disease), where it was transmitted to humans in forested areas from infected animals and from infected humans to others. For infected individuals who were living outside Africa, it was a result of the travel to African countries and the trade of animals from these countries to outside Africa. were that it is transferred from infected animals to humans in forested areas in south and middle Africa. In May 2022, the World Health Organization reported 257 confirmed cases and 120 suspected cases in 23 countries outside Africa, and most cases were in men who have sex with men and were self-infected. In June 2022, 35 confirmed cases were found across the USA.^1,2

How the 2024 monkeypox strain is different

There had been a previous outbreak of monkeypox in 2022, and it is only two years past, and a new outbreak in 2024. 

Monkeypox strains causing both 2022 and 2024 outbreaks are presented in two clades:

• Clade II: was responsible for the last virus outbreak in 2022
• Clade I: is the mutant strain of the previous clade II, the mutation in the virus genome that overcomes the body's immunity more than the previous strain

Despite the similarity of both regarding the flu-like symptoms of fever, a rash with bimbles and blisters, there are distinctive differences such as:

• Severity and fatality: the latest outbreak in 2024 caused by clade I was showing less severe symptoms, but a higher fatality rate reached 30%. However, the strain responsible for the 2022 outbreak showed more severe symptoms, but the fatality rate was 10%
• Transmission and spread: Clade I showed a wider spread than Clade II; in 2022, Clade II was endemic to central and west African countries, with fewer cases outside due to the initial exposure to the infecting virus in Africa during travel or being in close contact with infected animals or individuals. But in the case of 2024, there had been many confirmed cases worldwide, which was the reason to declare it an outbreak emergency by WHO
• The 2022 outbreak mainly affected men who had sex with other men, but the 2024 outbreak mostly affected female sex workers and their clients.^3,4,5

Overview of available monkeypox vaccines

The most efficient way to protect and treat any viral outbreak infection is vaccination, and monkeypox vaccines are no exception. Before the 2024 outbreak, two US FDA-approved vaccines showed proven efficiency in slowing down the spread of the smallpox viruses and the subsequent strains of monkeypox viruses (ACAM2000 and Jynneos). Both vaccines were initially used for the control and treatment of smallpox in 2000, but due to the similar genetic structure of the smallpox and monkeypox viruses, they exert a similar therapeutic efficiency.⁶

Jynneos(Imvamune/Imvanex)

It is a third-generation vaccine approved by the US FDA. Unlike traditional vaccines, Jynneos is a live virus vaccine that does not replicate in human cells. This makes its use safer in individuals with weakened immune systems. The recommended administration dose is two shots 28 days apart. Due to its safety and negligible side effects, it is the first choice for the protection of individuals at high risk, like healthcare providers who are in close contact with the infected populations.

ACAM2000

It is a second-generation vaccine approved by the US FDA. ACAM2000 is also a live vaccine, but it can replicate in human cells, which makes it need much attention to the subsequent complications. It may induce significant cardiac adverse effects, which is why it requires careful follow-up when administered to individuals with weakened immune systems. The recommended administration is a single dose. 

How vaccines work against monkeypox

The main mechanism by which the vaccines work against monkeypox is through what is called cross-reactivity. When the vaccine provokes the immune system to act against an introduced antigen-viral protein, the immune system of the body recognizes this intruder and forms antibodies, which act as a defensive guard against such viruses or similar antigens.

When the individual is exposed to a real virus, his immune system recognizes the previous antibodies and takes instant defensive action by killing the virus and preventing any progression of the disease. 

This is how Jenneos and ACAM2000 work.

But in case the virus mutates or changes its genome structure to disguise itself from the antibodies, this makes the human immunity system making it vulnerable to the disease and may not be fully protected by the previous vaccination.^7,8

Impact of the 2024 monkeypox strain on vaccine efficiency

The 2024 mutant strain of the monkeypox virus makes the previous vaccination unlikely to be fully protective and effective. 

Reduced efficacy due to viral mutation

Mutations that happen in virus strains are a result of changes in the virus’s surface protein. These proteins have a role in how the virus enters the host cells. That is why a mutant virus is not recognized easily with a previously vaccinated person’s immunity system.

Scientific research reveals that although Jenneos and ACAM2000 offer some protection against the recent 2024 monkeypox virus, it is not granted that they will offer complete protection against it due to this mutation. In other words, this mutation makes the virus more resistant to current vaccines than other previous viruses.

Scientific findings on vaccine response to the 2024 strain

The current studies aim to assess comparability between the immune response of the current vaccines to the current break of mutant strains in 2024 and that of the previous outbreaks. The primary findings indicate that the neutralization antibodies to the 2024 virus are less than the neutralizing antibodies for the previous viruses. 

This is a clear indication that current vaccines are less effective against the virus of the 2024 monkeypox.

The World Health Organization (WHO) declares that there is a crucial need to:

• improve the efficacy against the new strains
• booster doses to contain the progression of the spread
• update vaccine formulations to give safe and effective protection and treatment against new strains

Breakthrough infections and their implications

These implications include:

• The need for the adaptation of a new vaccination strategy to mitigate the public health risk. Although the current outbreak is less severe, there is a wide range of cases in vast regions
• The virus is adapting and going on mutation, which explains the widespread and decreased efficacy of the vaccines
• Health authorities in some countries take the initiative to give immunity-compromised individuals enforcement booster shots, especially for health care providers, weakened immunity persons, and individuals in close contact with infected people

Future directions in vaccine development

The emergent 2024 monkeypox posed a critical need for new vaccine development to overcome the decreased efficacy of the current vaccines and readiness for possible virus mutations in the future.

The need for updated vaccines

The scientific community focuses on discovering new vaccine formulations with new modes of action:

Biomarker-based therapy

They are biological indicators for the diagnosis and detection of the disease. Early detection and linking it to the infectious virus type, such as the monkeypox virus, will accelerate the therapy update for non-addictive treatment.⁹

Silver nanoparticles-based therapy

Nanotechnology presents a potential antiviral therapy in the future, as in the case of the monkeypox virus. Because of the tiny particle size, they can disrupt viral processes and increase the effectiveness of the existing vaccine treatments. Research indicates that silver nanoparticles can inhibit the virus without affecting the healthy cells, which makes it a good innovative approach and cost-effective antiviral in the future.⁹

mRNA vaccines as a potential solution

After the proven success of the mRNA vaccine in controlling COVID-19, this raised the attention to use the same technology in creating the monkeypox vaccine. The mRNA vaccine's role is to order the cells to develop viral proteins that enhance immune responses, and its production is quick. That supports the prompt production of new vaccines against the mutating viruses of the monkeypox virus.⁶

The importance of maintaining vaccine coverage

Vaccination is still the main role for protection and treatment against the monkeypox virus; despite the recognized decreased effectiveness due to mutation, it still offers protection.

Since the eradication of the smallpox vaccine in the 1980s and the stoppage of the vaccination, there has been a population within 20 years and more who were not vaccinated to smallpox, and since both smallpox and monkeypox viruses are related to the same virus family, the spread of the 2022 virus and 2024 viruses reaches a catastrophic outbreak.

Public health strategies for managing the 2024 monkeypox strain

Key strategies are utilized by public health authorities:

1. Widespread vaccination campaigns

Especially in areas with high infection transmission rates and to healthcare givers and immunity-compromised individuals.

2. Boosters and revised vaccination protocols

Booster doses and updated vaccine intake schedules are generalized in infected areas and weak individuals who are susceptible to infection more than others.

3. Surveillance and genetic sequencing

The updated surveillance and the study of the protein mutations of the virus are crucial to be ready for the coming mutant strains with new or updated vaccines.

4. Public education
5. Spread the educational data among the public, raise awareness for protection, and take the needed precautions to avoid the spread of the infection in certain societies.

FAQs

What is monkeypox (Mpox)?

Monkeypox, or (Mpox) as the WHO's recent preferred term, is a viral infectious disease. It is transmitted from infected animals to humans. It is transmitted by being in close contact with infected persons, touching contaminated surfaces with the virus, or from the environment when people are in close contact with infected animals.

What are the symptoms of monkeypox (Mpox)?

The symptoms range from less severe to serious illnesses that require medical care in specialized healthcare facilities. The common symptoms include rash for 2-4 weeks accompanied by headache, fever, swollen glands (lymph nodes), muscle pain, backaches, fatigue, and low energy. The raches seem like sores or blisters on the face, eyes, mouth, hand’s palm, soles of the feet, anal region rectum, or vagina. The number of sores varies from single to thousands. The sores in the anal and genital regions may be highly inflamed with severe pain in the rectum and urination difficulties. Secondary complications due to bacterial infection to the inflamed areas in the skin may induce more severe complications in the blood, lungs, heart, and brain; these complications may require hospitalization and antiviral medication. 

Are gay or bisexual at higher risk of contracting monkeypox (Mpox)?

Gays, bisexuals, and men who have sex with other men are showing most cases of Mpox in the 2022/2023 outbreak. The fact that the virus is transmitted from person to person infects persons with sexual relationships, whether gay or bisexual. 

Summary

In 2024, the world witnessed a new viral outbreak of the latest strain of monkeypox. The global efforts to control the spread of the mutant strain of monkeypox were a tremendous challenge. The currently available vaccines still offer important protection, yet their reduced efficacy against the new easily transmitted and widespread virus. This issue highlights the need to develop a new treatment vaccination strategy and the need to continue the research to create more efficient vaccines without significant side effects. 

Scientists work on new vaccines with updated technologies, such as mRNA. The strategy to maintain high coverage of the vaccination has been planned to prevent the progression of the infection and slow down the virus’s spread among the population. The public health authorities utilize additional strategies such as elevating the awareness and alertness of the individuals, conducting genetic surveillance, and publishing-related boosters. These strategies aim to mitigate the impact of the new mutant virus spreading around the globe, not only in localized areas of endemic threat.