President Emmerson Mnangaga claimed on his Twitter account that Victoria Falls has reached herd immunity against Covid-19 after 77% of the city’s adult population got vaccinated.
BY ZIM FACT
On March 24, the government launched a mass vaccination programme in Victoria Falls, targeting the city’s entire adult population, estimated at 25 000 people.
According to official statistics, 19 243 Victoria Falls residents had received their first dose by April 21, which also happened to be day 28, when second doses started falling due in the city. That day, 1 514 got their second shot.
Disaggregated figures for the days leading up to April 25, when Mnangagwa made his claim, are not available. However, nationally, 17 567 second doses were administered between April 21 and 25.
Even assuming that all these were administered in Victoria Falls, which is improbable, the city would still not attain the 77% second jabs claimed by Mnangagwa.
The World Health Organisation (WHO) defines herd immunity as the protection from an infectious disease that a population gets from previous infection or vaccination.
WHO says it only supports the attainment of herd immunity through vaccination and not through allowing infections to spread unchecked through populations.
The global health watchdog also says it remains unclear at what level herd immunity against Covid-19 can be attained.
“We are still learning about immunity to Covid-19. Most people who are infected with Covid-19 develop an immune response within the first few weeks, but we don’t know how strong or lasting that immune response is, or how it differs for different people. There have also been reports of people infected with Covid-19 for a second time,” WHO says.
“Until we better understand Covid-19 immunity, it will not be possible to know how much of a population is immune and how long that immunity lasts for, let alone make future predictions.”
However, some experts believe herd immunity against Covid-19 can be achieved if between 60-70% of the population is vaccinated. For more contagious infections such as measles, the herd immunity threshold is much higher, around 95%
Mnangagwa’s claim that Victoria Falls has achieved herd immunity against Covid-19 is incorrect. The calculation yielding the 77% claim seems to arise from the 19 243 people who officials say had received their first vaccine dose, out of the city’s targeted 25 000 adult population. With the double-dose vaccines Zimbabwe is currently using, one is only considered to be fully vaccinated after the second shot.