COVID-19: Is the second wave of coronavirus approaching?

Virologists predicted the second wave of infections months ago. The more the rules and restrictions introduced to combat the coronavirus are relaxed, the greater the risk of a second wave. Now this one seems to be coming.

In many countries, the lockdown is no longer as strict. Germany, Spain and Greece were the first countries to lift the restrictions. The World Health Organization (WHO) fears that the coronavirus may never disappear again, and warns of the possible consequences if people take the situation lightly and return to the behavioral habits that prevailed before the coronavirus.

In many countries, stores have reopened, as have restaurants. In Australia, after several cases of infection among pub and bar guests, the government has tightened restrictions again.

People's desire to travel is also increasing again and is another reason for the increased contagion rates. In Germany, there was a sharp increase in the number of infections in late July. The reproduction rate R also went up again.

The playback number R

The R value indicates the number of people that a person carrying the SARS-CoV-2 can transmit on average. This number helps to better predict new infections. For example, if R is 3, it means that one person with coronavirus will infect three more people. If the breeding number is 1, the infection rate remains more or less the same.

In Germany, this reproduction figure exceeded 1 in late July. Among other things, this could be due to vacationers re-gathering in large crowds, although the pandemic is far from over.

The second wave

There is no uniform international standard for the definition of a second wave. Even the WHO doesn't have clear guidelines. This organization's spokesperson, Christian Lindmeier, wrote in an email to DW: "The term refers (only) to new outbreaks that have occurred after an initial decline. The same applies to a 'third' wave."

Already at the beginning of the pandemic, virologists warned of a new wave of infections and appealed to the population not to consider the decrease in contagion figures as a license to act without concern.

Scientists compare the coronavirus with the Spanish flu that ran from 1918 to 1920. According to the WHO, it claimed 20 to 50 million lives worldwide. That pandemic unfolded in three waves. The second wave was much worse than the first and caused many more deaths. Between the phases of each of them, the virus mutated. The same could happen with the coronavirus.

If the virus mutates

All viruses can mutate, that is, change. In the best case, a virus is weakened by a mutation. This means that it is less dangerous and that it takes fewer victims. For this to happen, however, many people must already have developed an immunity to the coronavirus. Scientists do not yet know, if this is the case with SARS-CoV-2.

People develop immunity against most viruses. Once infected, the body produces antibodies, which make it immune. The virus can no longer harm the person. It is unclear whether this also applies to the coronavirus.

An increasing number of cases indicates that some patients with COVID-19 no longer have detectable antibodies after just a few months. This could also mean that they could become infected again.

During the rise of the coronavirus, there were many voices saying that only a so-called "herd immunity" could contain the pandemic. Group immunity occurs when a high percentage of the population is already immune. Then the pathogen can no longer spread as quickly. Between 70 and 90 percent of the population would have to be immune to a virus to stop it.

The specialized journal "The Lancet" recently published a study on "herd immunity". According to him, it is something that cannot be achieved against the coronavirus. Scientists from the Carlos III Health Institute in Madrid, the Spanish Ministry of Health and Harvard University in Boston participated in the antibody study, the largest in Europe to date, with 60,000 people.

The tests showed that only 5 percent of Spaniards had developed antibodies against the virus.

Source: Gudrun Heise for DW