As the UK eases out of lockdown the question I have been asked many times is, “Will there be a second wave of COVID-19 infection?”
Both broad sheet and tabloid press are running headlines such as, “Second more deadly wave of coronavirus expected to hit Europe this winter” (1) and “UK coronavirus second wave will be 'massive' if Britons do not take vital action.” (2)
On 7 June 2020 the BBC World Service ran a long article entitled “Coronavirus 'second wave': What lessons can we learn from Asia?” in which assertions were made that a second wave was inevitable and could be more devastating. (3)
What is a Second Wave?
The medical definition of a second wave is “A phenomenon of infections that can develop during a pandemic. The disease infects one group of people first. Infections appear to decrease. And then, infections increase in a different part of the population, resulting in a second wave of infections.” (4)
They are a recognised feature of all pandemics but mean a recurrence of the same infection, not a new wave of more deadly infection. The media has constantly likened the current pandemic to the 1918 Spanish Flu which killed up to 50 million people and came in apparent waves. However it is not wise to compare two events separated in history by more than 100 years. In 1918 it was impossible to collect patient data or viral samples the way we can now for COVID-19. We cannot extrapolate data from a pandemic last century, which was caused by a completely different type of virus, in the hope it will tell us how COVID-19 will behave now. (5)
Have Countries Who Have Eased Their Lockdowns Experienced a Second Wave Yet?
In the countries first affected by COVID-19 such as China, Japan and South Korea there has been a spike in new infections in some regions but not across the entire country. These countries have reinstated lockdown in the areas where new clusters of disease have sprung up rather than implementing a countrywide lockdown.
In Japan, the island of Hokkaido had a second wave of infections after lockdown rules were relaxed. It imposed its first lockdown in late February and by the middle of March the number of new cases per day had fallen to single figures. By April the area was out of lockdown but in May it was hit by a second wave of infections and lockdown was re-imposed. This second lockdown is now being lifted. (6)
In Shulan in north-east China lockdown was re-imposed when a surge in new cases was detected on 17 May. (7)
In South Korea, an outbreak at a logistics centre near Seoul led to lockdown measures being re-implemented in the area on 27 May. (8)
In all three cases, lockdown was only imposed on the affected region, not the entire country.
Meanwhile, Iran is seeing a new surge in infections which some experts say is a result of easing lockdown restrictions too soon. Kamiar Alaei, an expert on Iran's public health and president of the Institute for International Health and Education in Albany, New York said, "There is no coordination between the trend of infections and the government's decision-making," and that "a new peak is inevitable every time restrictions are lifted without a steady and constant decrease in the number of infections for two weeks.” (9)
In Europe, cases of COVID-19 have continued to fall as lockdowns have been eased. Some countries have experienced regional spikes in cases but in all cases it has been possible to trace the origin of the new outbreak.
Italy is bracing itself for a second wave that so far has not materialised. Lockdown began to be eased on 18 May and businesses, churches and tourist sites (but not schools) are now open with strict social distancing measures in place. (10)
In Germany, which began easing lockdown at the end of April, there have been some clusters of reinfections connected to indoor gatherings, primarily church services and family parties and at meat packing factories. (11)
In Belgium, one of the worst-hit countries in Europe, there has been no disease spikes. Steven Van Gucht, a virologist and advisor to the Belgian health authority has said, “I was also expecting a scenario where the numbers would have stabilized, maybe a small rise. It would have been natural. But we don’t see that for the moment.” (12)
In France there was an initial increase in daily cases as lockdown was eased but numbers are now declining. (13)
In Spain, there has been several small outbreaks linked to private parties. (14)
Norway and Denmark were the first European countries to reopen schools and their case numbers have continued to decline. (10)
Factors that influence a second wave
Environmental Factors
COVID-19 is more likely to spread in confined, indoor spaces. There is also some evidence that infection acquired from such places will be more severe than that acquired in outdoor spaces because people are exposed to a higher amount of virus in confined spaces compared to exposure outside.
In Hong Kong researchers found that clusters of infections were more common in bars and clubs than at home or work and that large outbreaks were linked to churches, factories and care homes. (15)
A study in Japan found that the risk of infection indoors is almost 19 times higher than outdoors. (16)
Knowing where COVID-19 clusters are most likely to occur can influence decision making on when and how to lift lockdown restrictions. The clusters connected to churches is thought to be linked to singing and in factories clusters are more common in noisy factories where workers have to shout to be heard. Gwenan Knight from the London School of Hygiene & Tropical Medicine noted that, “Maybe slow, gentle breathing is not a risk factor, but heavy, deep, or rapid breathing and shouting is.” (17)
The Role of the Super-Spreaders
Super-spreaders are people who excrete a higher than usual amount of virus meaning they are more likely to infect other people than a typical infected person. They may not be ill themselves.
“Typhoid Mary” is one of the world’s most famous super-spreaders, a woman who, in her work as a cook in the 19th century, spread typhoid to seven out of eight families she worked for whilst remaining well herself. (18)
Super-spreaders have been identified for COVID-19. A Hong Kong study estimated that 80% of cases in Hong Kong came from just 20% of the infected people. (19)
This phenomenon makes it hard to predict when an increase in cases might occur as an area with a high number of super-spreaders is more at risk of a sudden surge in cases than one with a low number.
SARS and MERS are two respiratory illnesses also caused by coronaviruses which behave in a similar way. In both their outbreaks clusters of infection were traced to super-spreaders at close gatherings. (20)
Social events attended by super-spreaders can quickly undo the effects achieved through lockdown. However, a person has no way of knowing if they are a super-spreader. Many are asymptomatic and scientists do not yet understand why some people are affected in this way. Super-spreaders are only identified by tracing backwards through a disease outbreak and that can lead to stigmatisation of the person involved as happened in the UK when the press named a man identified as a super-spreader. (21) (22)
Climate
Some viruses have a predilection for certain types of weather. The influenza viruses favour winter as do some of the other members of the coronavirus family.
It is too soon to know if COVID-19 will follow a seasonal pattern but it is possible that the northern hemisphere will see an increase in cases in the wintertime. (23)
Underlying Immunity
During the 2009 swine flu pandemic it came as a surprise to scientists that the very elderly appeared to be less affected than younger generations. The virus was subsequently found to be have a similar structure to the flu virus from the 1918 Spanish Flu pandemic and it transpired that the very elderly had gained an immunity during the 1918 outbreak that protected them against the 2009 outbreak.
Extrapolating to the current pandemic a few scientists have postulated that some people may have immunity to COVID-19 through exposure to similar coronaviruses in the past. However most scientists are not of this view pointing out that immunity to coronaviruses is not thought to last very long, often less than a year, and that the COVID-19 virus is different in structure to other known coronaviruses.
It is unlikely that previous exposure to other coronaviruses will give immunity but even more significant is that having COVID-19 may not confer lifelong immunity either. Epidemiologists at Harvard University in the USA have predicted that COVID-19 will occur in sporadic outbursts until 2025 as immunity comes and goes in the population. (24)
How can a Second Wave be Prevented?
Looking at the experience of other countries around the world offers some insights as to which measures could play a role in preventing an overwhelming second waves of infection.
Lift lockdowns Slowly and Carefully
Opinions on lockdown have differed between countries and within countries, and politicians and scientists have expressed diametrically opposed views.
However it is becoming increasingly clear that the spikes of infections seen when lockdowns are eased can be traced back to gatherings of people in confined spaces who are not adhering to social distancing measures as can be seen in the examples cited above in Germany and Spain.
The USA has had a varied approach to lockdown because of the devolution style of government whereby individual states, and even counties and cities within those states, could set their own parameters around lockdown. Some states were slow to instigate lockdown and quick to lift it. Many states are reporting their highest numbers of daily new cases and the seven day average is increasing not declining. (25)
There is a dedicated piece on the USA here.
Texas was one of the first states to lift its lockdown measures allowing all businesses including hair salons and tattoo parlours to reopen in mid-May. It now has more new cases each day than before it imposed lockdown. (26) (27)
The same is true in Florida where again, daily numbers are increasing and are above those before lockdown. It was one of the last states to impose lockdown measures and one of the earliest to lift them. (28)
New York, which was badly hit at the start of the US pandemic, adopted an approach closer to that of Europe and its figures are steadily declining with no uptick in cases as lockdown eases. (29)
The situation in the USA shows that lifting lockdown before case numbers are well beyond the peak leads to a resurgence of infection, sometimes beyond the numbers prior to lockdown.
Quarantine visitors from abroad
The UK now requires people to self-quarantine for 14 days on arrival in the UK. (30)
Some have questioned the need to do that now, when the pandemic is past its peak in the UK and there were no such rules in place before.
The aim of the quarantine to stop the number of imported cases exceeding local cases. In an ideal world quarantine should begin the moment a disease outbreak begins. For countries everywhere that would mean closing borders at the very start of an outbreak when in reality there is very little public or political will to do so.
At the start of this pandemic it was thought that human to human transmission of COVID-19 was not happening. By the time it was realised that this was the main mode of transmission millions of people had been flying around the world spreading it. (31)
Once cases in a country start to rise rapidly it is too late to quarantine, it has very little effect on numbers. However once case numbers are declining, it makes sense to instigate a quarantine for incoming travellers to try and stop the disease being re-imported into the country. During lockdown very few passenger flights were coming into the UK but that number is set to increase dramatically as lockdown eases. (32)
The UK is not alone with this measure. Every European country has some degree of restriction. (33)
In China in March, all Beijing-bound international flights were diverted to other cities where passengers were quarantined. (34)
In Hong Kong overseas visitors wear an electronic bracelet so that their movements can be tracked to ensure they are self-isolating. (35)
Track and Trace.
Track and trace enables new cases of COVID-19 to be identified and their close contacts advised to self-isolate. You can read more about the UK’s “Track and Trace” policy in this piece here.
A robust track and trace system allows new disease outbreaks to be quickly identified and hopefully shut down.
South Korea has a system that uses apps and GPS technology to track down cases allowing them to respond to local outbreaks swiftly. For example a new cluster of cases around 12 May was traced back to nightclubs in Seoul and 90,000 people were contacted through their track and trace system. (36)
Finding and testing new cases quickly and tracing their contacts is a vital way to stop secondary outbreaks.
Behaviour - Masks, Social Distancing and Hand Washing
Debate has raged about the use of facemasks as a means of reducing the transmission of COVID-19.
You can read more about facemasks here from a piece written on 7 April.
Scientists at Cambridge and Greenwich universities have given weight to the wearing of facemasks in public places after they released a report stating that masks could reduce transmission rates. They did however say this should be in conjunction with other measures such as social distancing. Richard Stutt from Cambridge University said that, “Our analyses support the immediate and universal adoption of face masks by the public,” but he went onto say it should be combined with “social distancing and some lockdown measures.” (37)
The WHO (World Health Organization) has now updated its guidance on facemasks asking people to wear them in public places. (38)
Not all scientists agree, not least because the Cambridge and Greenwich findings are reached by disease modelling, a mathematical approach open to error.
Brooks Pollock, an infectious disease modelling expert at Bristol University, said that, “the likely impact of masks could be much smaller than predicted.” (39)
As schools, businesses and shop reopen in the UK, there is no doubt that people will have to behave differently. Staying 2 metres apart from each other, wearing masks and regular hand washing (or sanitisation in public places) will play an essential part in preventing a rise in infections.
In Conclusion
Whilst speculating about a second wave of COVID-19 we perhaps should remember that the first wave is not yet over.
There are still many unknowns about this virus such as how it will respond to weather patterns, if it can re-infect a person, how many people are likely to be super-spreaders. All of these will influence the risk of further waves of infection.
However we can try to influence the future with what we do know. We know the virus spreads the most in crowded and confined spaces and that the presence of super-spreaders at crowded events causes a sudden upsurge in cases. We know it can be imported by international travel and that by keeping socially distanced we can stop it spreading.
A second wave of infection is not inevitable but to try and avoid it we will need to accept continuing with some level of restrictions in our daily lives. This will become harder as people yearn to return to normal and begin to resent the measures needed to control the virus. In the end a backlash against the restrictions protecting us from a second wave may be the very thing that causes one. It will likely be human actions, rather than anything the virus does, that allows a second wave to happen.
