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We asked readers what they wanted to know abut the science of the coronavirus. Our science correspondents Nicola Davis and Linda Geddes have the answers.
Why is it taking so long to get a vaccine?
Why does a vaccine take so long to make and will it be a case of being injected with a trace of the virus itself? Jane, lampshade maker, Betchworth
There are hundreds of vaccines in development to tackle Covid-19, and several different approaches are being taken. Some involve presenting the body with a weakened or inactive version of coronavirus, while others involve presenting the body with the so-called spike protein that is found on the surface of coronavirus and is the means by which the virus enters our cells. Once exposed to this protein, the body produces antibodies and other immune responses to guard against infection.
The Oxford vaccine delivers the gene for this protein to human cells via a chimpanzee cold virus that has been changed so it cannot grow and cause an infection. Once this is inside our cells, the spike protein is produced from the DNA. By contrast, a vaccine from the US company Moderna is based on a new approach using genetic material called mRNA to trigger human cells to produce the spike protein.
The process of vaccine production is typically lengthy, and for good reason. Vaccines must pass through a series of trials to show they are safe and effective. It is also necessary to determine how long any protection lasts and whether booster shots are needed, and whether the level of protection is lower for certain groups, such as older people.
A report commissioned by the Royal Society sheds light on some of the other hurdles that must be overcome before a vaccine is ready, from issues over scaling up manufacturing to the logistical challenge of administering the vaccine to large numbers of people.
Sir Patrick Vallance, the UK government’s chief scientific adviser, has said a vaccine for widespread use is unlikely to be available before spring next year. Even this would be an incredible achievement: on average, he said, it takes 10 years to produce a new vaccine from scratch.
What do we know about schoolchildren and infection rates?
Shortly after schools reopened, cases skyrocketed and haven’t stopped. I’ve heard reports that not many schoolchildren are testing positive. Is this because they simply aren’t catching the virus? Or is it because the advice is to only get a test if you have symptoms, which schoolchildren are likely to not get? Mark, works for a charity, Wallasey
It’s a hot topic but answers are thin on the ground. One study, published in the journal Jama Pediatrics and based on data from around the world, suggested that primary school-age children were about 40% less likely than adults to be infected. But studies are still exploring children’s ability to pass on the virus.
“It’s an excellent question, to which we don’t really have a very satisfactory answer,” said Prof John Edmunds, of the London School of Hygiene & Tropical Medicine. “There is a study that is just starting which is aimed at working out the extent to which kids to get infected and pass it on. At the moment we don’t really know with any great certainty.”
Edmunds said it was known that children were more likely to develop no symptoms if they were infected, or to show only very mild symptoms. “So, some of the effect will be – as your reader says – to do with this. But whether this is sufficient to explain the pattern is another matter.”
How many people are dying from Covid-19?
I, and others, would like to know how many people have died of the virus rather than with the virus.Why [use] this methodology which inflates the figures? Stephen Rice, works in a hospice, Preston
There are several different ways of looking at Covid deaths, all of which have different strengths and weaknesses. For example, the daily figures released by the government relate to deaths of people who tested positive for Covid in the past 28 days, and are given by date reported. Numbers by date of death are also given, although this has a time lag. Public Health England says there are good reasons for taking this 28-day approach, noting that although Covid may not have played a role in some of the deaths, it is difficult to rule it out. The PHE data is available daily, giving a rapid snapshot of trends.
The Office for National Statistics takes a different approach, looking at death certificates for mentions of Covid. It is not necessary for someone to have tested positive for Covid for the disease to appear on the death certificate, but a doctor would need to record it as either the underlying cause of death or as a suspected contributing factor. Once a week the ONS provides an update of total number of death certificates mentioning Covid.
The ONS recently released data on deaths due to Covid and those in which Covid is mentioned on the death certificate as a contributing factor but not the chief cause of death. Between 1 January and 31 August, Covid was mentioned on the death certificate of 49,686 people in England, 45,797 of which had Covid as the underlying cause of death.
In terms of “inflation of deaths”, the total number of deaths recorded by the PHE approach is lower than the number recorded by looking for Covid on the death certificate, while the data above suggests the vast majority of the latter are deaths caused by Covid.
Why is there a north-south divide?
What does the science say about possible reasons for the north-south divide in infection rates? Jane Twyman, catering assistant in the arts, Lancaster
There are probably several factors at work. The first is population density. Covid-19 is a highly contagious disease, and spreads best in densely populated areas such as large cities, where people have a higher probability of coming into contact with others, including those from other areas. This is likely to be why London bore the brunt of the first wave – not only did it have large numbers of commuters travelling in on public transport each day and mixing in the workplace as well as socially, it is also a huge international hub, with infectious people potentially arriving from abroad.
But London contains a larger than average number of white-collar workers who are now working from home, significantly reducing the level of mixing. The nationwide lockdown also drove down the number of infections in the capital to very low levels, unlike in the north where they are thought to have remained quite high. Once lockdown restrictions were relaxed, those seeds of infection quickly spread in densely populated northern areas. Infections are now also taking off in London again.
The second major factor is socio-economic deprivation. A greater proportion of the workforce in the north-west and Yorkshire and the Humber are employed in the manufacturing, wholesale and retail industries, or work in health and social care. People in these jobs are more likely to have had to continue working during lockdown, possibly using public transport to get to work. Financial pressures to continue working also make it harder to comply with social restrictions, and cramped housing makes it harder to self-isolate if you become infected.
Does vaping spread Covid?
In the street I often have to walk through vape clouds. Can the clouds contain coronavirus? Phil Viner, writer, Brighton
Prof Caitlin Notley, of Norwich Medical School at the University of East Anglia, told the Guardian it was certainly possible. “Someone infected with coronavirus clearly would be emitting viral [particles] in their vape if they were vaping, just the same as they would if they were breathing out or singing,” she said. “The thing with vaping is it makes breath visible and so when you are outside you can see huge clouds of vapour floating away in the wind.”
Notley said this underlined the need to wear masks, and for people who vaped to be considerate of others. But she said there was no evidence to say whether vape clouds were more of a problem when it came to passing on an infection than normal exhalations.
“It is not a good idea for anyone to be exhaling big clouds of vape or singing loudly in a crowded area and sharing their exhaled breath with other people,” she said. “Of course, we would not want to discourage people from vaping if they have successfully managed to quit smoking.”
Source: The Guardian
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