Measles is one of the oldest diseases still circulating in third world countries.
The first cases of measles were recorded in the seventh century, and if a person is not vaccinated, the mortality rate is between 15 and 25 percent, according to the Centers for Control and Prevention of Infectious Diseases in the United States (CDC).
Due to the length of measles, it is not possible to determine how many lives the disease has lasted.
According to the World Health Organization, measles is the most contagious, and 92 to 95 percent of the population had to be immunized so that the remaining five to eight percent could not get sick.
Polio, which is also a very dangerous disease, was recorded in the 18th century and most often affects children between the ages of three and eight.
Before the vaccine appeared in the middle of the last century, the mortality rate was from two to five percent in children, from 15 to 30 percent in adults, and this percentage increased with brain complications to 75 percent.
The WHO adds that the percentage required to obtain collective immunity against polio (transmitted by the oral-fecal route) is approximately 80 percent.
Smallpox or smallpox is probably the oldest disease today, because it originated about 3000 years ago in India.
WHO data show that without vaccination, mortality is 30% and survivors often have permanent scars.
It is not known how many people died from the virus.
According to WHO experts, 80 percent of people need to be immunized in order to neutralize smallpox (transmitted by air and droplets).
The pertussis vaccine was manufactured in 1926, but according to the US CDC, there are currently 24.1 million patients in the world and 160,000 people die each year.
According to data from Harvard, for whooping cough (transmitted by air and droplets), 92-94 percent of the population must be immune to protect the rest.
Mumps is also a very old disease that was first reported in the fifth century, and the mortality rate per 10,000 population is between 1.6 and 3.8 percent due to complications caused by inflammation of the brain.
Harvard data say that mumps, which are transmitted by air and droplets, require immunity between 75 and 86 percent of the population, and the vaccine was made in 1967.
In developed countries, the mortality rate for rubella virus (airborne and droplet transmission) is between 0.05 and 0.1 percent per 1,000 cases, which is significantly less than in third world countries, where the death rate is between three and six percent.
The virus was registered in 1815, the vaccine was manufactured in 1967, and is estimated to have produced between 83 and 85 percent of the immune system, according to Harvard.
SARS was discovered in 2002 in China and was active until 2004 and is transmitted by air and droplets.
The WHO estimates that the mortality rate was around 11% at the end of the epidemic, which affected four countries in addition to China.
When the WHO declared the end of the epidemic in July 2003, 8,098 people became infected and 774 died, although there were several cases the following year.
The vaccine does not yet exist, although the virus has mysteriously disappeared.
For SARS (airborne and droplet transmission), it is estimated that 50 to 80 percent of the population must be immune to stop the spread.
As for Ebola (transmitted by body fluids), which is the most dangerous of these viruses, the mortality rate is about 50 percent.
The first case was reported in the Congo in 1976 and it is estimated that more than 80 percent of people need to be vaccinated to gain herd immunity, but this number is uncertain because it is uncertain how long it can protect against Ebola. the US FDA (Food and Drug Administration) approved the first vaccine in 2019.
In addition to Ebola, the “cousin” Kovid-19 – MERS – is a great threat to humanity.
MERS belongs to the group of coronaviruses and the first case was recorded in 2012 in Jeddah, Saudi Arabia, and the mortality rate was between 34 and 35 percent between January 2020, according to the WHO.
Of the 2,519 deaths, 858 were and MERS is also called camel disease, which transmitted the virus to humans.
It is still not entirely certain whether it is transmitted only by droplets or whether there are other modes of human-to-human transmission.
For covid 19, one of the airborne and droplet-borne coronavirus viruses, researchers still cannot agree on the percentage of immunity necessary for the herd’s immunity, especially since it is a virus that returns after a few months and not everything about him is known yet.
So far, more than 1.5 million people have died on covide 19, almost 70 million cases have been infected worldwide, and 60 to 80 percent of people need immunity to stop the spread and scientists still disagree.
Collective immunity, or “herd immunity,” develops when most individuals in a community develop immunity to a disease that prevents the transmission of the disease, so that the entire community is protected, not just those who are immune to the particular disease.
In order to develop collective immunity, it is first necessary for the infection to spread in order for people to be vaccinated, so that a different percentage of different diseases are needed to develop “herd immunity”.