Effective Vaccines for Protection Against Monkeypox- A Detailed Guide

Monkeypox is a rare viral disease caused by the monkeypox virus, which belongs to the same family as the variola virus, the cause of smallpox. The symptoms of monkeypox are similar to those of smallpox, though generally milder. These include fever, rash, swollen lymph nodes, and muscle aches, often leading to painful lesions. Although the virus was first identified in monkeys, it mainly spreads through rodents in parts of Central and West Africa. However, recent outbreaks have caused global concern, leading to questions about how to protect oneself from the virus. One of the most effective ways to combat this disease is through vaccination.

Vaccines for Monkeypox

Historically, there has been no specific vaccine developed exclusively for monkeypox. However, because the monkeypox virus is closely related to the smallpox virus, vaccines originally designed for smallpox have been found to be effective in preventing monkeypox as well. Two major vaccines are currently recommended for preventing monkeypox-

1. ACAM2000 (Smallpox Vaccine)

The ACAM2000 vaccine is a live virus vaccine originally developed to protect against smallpox. The live virus used in ACAM2000 is a weakened form of the vaccinia virus, a cousin of the smallpox virus, which stimulates the immune system to fight off the infection. Although the vaccine is primarily designed for smallpox, studies show that it can offer protection against monkeypox due to the genetic similarities between the two viruses.

How It Works

ACAM2000 works by introducing the vaccinia virus into the body, which doesn't cause disease but triggers an immune response. This immune response can protect against both smallpox and monkeypox. However, ACAM2000 is a second-generation vaccine, meaning that it carries some risks. It can cause side effects such as fever, rash, and, in rare cases, heart problems or a localised infection at the injection site. Because of these risks, this vaccine is generally recommended for individuals who have been exposed to the virus or are at high risk, such as healthcare workers or lab personnel handling the virus.

Effectiveness Against Monkeypox

The ACAM2000 vaccine provides strong protection against the monkeypox virus, with an estimated effectiveness of about 85%. While this is lower than the protection rate seen for smallpox, it is still considered highly effective in reducing the severity and spread of monkeypox. One dose of the vaccine is typically sufficient, though certain high-risk individuals may require a booster shot.

2. JYNNEOS (Modified Vaccinia Ankara-Bavarian Nordic Vaccine)

JYNNEOS, also known as Imvamune or Imvanex, is another vaccine that has been developed to protect against both smallpox and monkeypox. This vaccine is a third-generation vaccine, meaning it is a more advanced and safer option than earlier vaccines. JYNNEOS contains a non-replicating form of the vaccinia virus, which makes it safer for people with weakened immune systems or other health conditions.

How It Works

Unlike ACAM2000, the JYNNEOS vaccine contains a modified form of the vaccinia virus that cannot replicate within the body. This means that the risk of side effects is much lower, making it a suitable option for a broader population, including people with compromised immune systems. JYNNEOS is administered in two doses spaced four weeks apart and provides lasting immunity against monkeypox.

Effectiveness Against Monkeypox

JYNNEOS is highly effective against both smallpox and monkeypox virus, with clinical trials showing a strong immune response after the two-dose series. It is considered a safer alternative to ACAM2000 due to its fewer side effects and the fact that it doesn’t use a live replicating virus. It is particularly recommended for those at high risk of exposure to monkeypox, such as healthcare workers or individuals living in areas with confirmed outbreaks.

Who Should Get Vaccinated?

The need for vaccination against monkeypox depends on several factors, including exposure risk and regional outbreaks. For the general public, mass vaccination is not typically necessary, but it becomes a priority for certain groups-

• Healthcare workers- Those who are treating patients with monkeypox virus or handling infected materials should receive the vaccine to protect against possible exposure.
• Lab personnel- Individuals working in laboratories that study monkeypox virus or related viruses are at a higher risk of exposure.
• High-risk populations- People living in or travelling to areas where monkeypox outbreaks are reported should consider vaccination, especially if they are in contact with wildlife or are in settings where the virus can spread easily.

In cases where an individual has already been exposed to the virus, post-exposure vaccination may be offered. Receiving the vaccine within four days of exposure can prevent the onset of the disease, while vaccination within two weeks of exposure may reduce the severity of symptoms.

Availability of Monkeypox Vaccines

Currently, both ACAM2000 and JYNNEOS are available in limited quantities, and their distribution is managed by health authorities based on outbreak status and exposure risk. The JYNNEOS vaccine has been approved for use in several countries, including the United States, Canada, and parts of Europe, while ACAM2000 is primarily used by the military and healthcare providers.

In regions where vaccines are not widely available, preventive measures such as avoiding contact with infected animals or individuals and practising good hygiene help reduce the spread of the monkeypox virus.