Vitamin D Levels and Ethnicity

Why is vitamin D so important?

• It helps regulate the amount of calcium and phosphate in the body. These nutrients are needed to keep bones, teeth and muscles healthy. A lack of vitamin D can lead to bone deformities such as rickets in children and bone pain caused by osteomalacia in adults.
• It is widely thought that vitamin D reduces the amount of 'stress hormone' cortisol within the body. Cortisol is linked to high blood pressure, in turn increasing the risk of cardiovacular disease.
• There is some evidence from small studies that vitamin D may give some protection against Covid-19.

 Sources of vitamin D

The main source of vitamin D for humans is sunlight, the level of which varies over the world. Around the equator, sunlight levels are high year round. As you travel north or south, the level of sunlight varies over the year, with lowest levels in the winter season. Natural sources of vitamin in the diet are oily fish, red meat, liver and egg yolks, though these contain limited quantities.

Ethnicity

People with dark skin are especially vulnerable to vitamin D deficiency due to their high melanin levels, which inhibit vitamin D production and protect against skin cancer. The level of vulnerability varies with the amount of melanin, so those with the darkest skin are the worst affected. As more people with dark skin ethnicity move to live or work in lower sunlight areas of the world, their vitamin D levels are not enough; a finding which is supported by some research in the US. Note this research was carried out some years ago, and uses the terms "black people" and "white people".

• One study found that 97% of "black" people and 70% of white people had vitamin D deficiency. 
• Another study found that "blacks" have half the vitamin D levels of white people.

Other social factors can also reduce exposure to sunlight. 

• Workers on permanent might shift will spend less time in sunlight.
• In some strict Muslim areas, women are kept indoors for much of the time. 
• Some cultures rate paler skins as being more beautiful; people may therefore restrict time spent in full sunlight, and/or cover most of the skin with clothing when outdoors.

Supplements

Therefore people (especially those with dark skins) in countries with big seasonal variations are advised to take supplements of the vitamin. A dose of 10 micrograms a day will be enough for most people. Taking too many supplements over a long period of time can cause too much calcium to build up in the body (hyercalcaemia) , which can weaken bones and damage kidneys and heart.

Sources: various

Herd Immunity

With the current Covid-19 pandemic, some people have been advocating allowing people to resume normal life, suggesting that at some point herd immunity will happen.

If enough people become immune to an infectious agent, the entire population (or a specific community) is protected  because infectious people rarely encounter a non-immune person, so the transmission dies out.

The level of individual immunity to get to herd immunity level for a virus depends on how infectious it is - measured by R, the average number of people that each infectious person infects.

• The classic example is measles, which has an R number of around 15 and a herd immunity threshold of 95%.
• For Covid-19 the R number is about 3.5 and the herd immunity threshold is thought to be around 60 to 70%.

Herd immunity has only ever been achieved by vaccination. This is because herd immunity can only be built if the immune response totally prevents individuals from picking up and transmitting the virus. That sometimes happens but often it doesn't. While a person's immune system may stop them from falling ill if they reacquire a virus, it doesn't prevent onward transmission. The same is true of vaccines.

'Letting the virus rip' would mean letting between two-thirds and three-quarters of the population catch the virus. There are a number of issues with this proposal.

• Collateral damage: even if the death rate is 1%, letting the virus run free will hospitalise and kill millions.
• We can't take it for granted that individual immunity will automatically create herd immunity, since we don't yet know what immunity a person gets from having survived Covid-19, and how long this lasts.
• While they survive a Covid-19 infection, some people are now experiencing the symptoms of 'long covid'. These symptoms can be severe, and affect more than one of the body systems.

So, herd immunity is not the answer.

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Can MMR Jabs Protect Against Covid-19

 A study by scientists from the University of Georgia claims that the MMR vaccine may protect some people against severe Covid-19 (a 29% lower chance), and may prevent some people from catching the coronavirus. Those with the highest antibody levels specific to mumps were 'immune' to Covid-19, but the same effect was not seen for measles and rubella antibodies. This is a possible explanation of why children only seem to get mild Covid-19 illness, if any at all.

Other scientists have also theorised that this could explain the lower Covid-19 death rate in continents with measle-free status, including Africa and Asia.

A team at Cambridge University found in April 2020 that part of the coronavirus structure is similar to mumps, measles and rubella.

All children in the UK are offered the vaccine and around 91% currently are immunised by their second birthday. The first jab is given from nine months old, and another before they are six years old. While antibodies fade over time, they can still offer some protection against viruses. Mumps antibodies decline by the age of 14, which is the same age as coronavirus prevalence increases sharply.

The MMR II vaccine (introduced in the early 1970's) is considered a safe vaccine with very few side effects. Study researcher Dr. Hurley suggests that adults over the age of 40 should be given the MMR jab if they have never had it.

Source: Various news media.

Welcome to 2021

 I don't usually write this sort of post but 2020 has been a difficult year. Wishing every reader and their family and friends a happy and healthy 2021.

Here are the bad bits.

• Boris Johnson was Prime Minister and Donald Trump was US President. Neither competent at dealing with the pandemic crisis.
• The UK finally leaves the EU - being in Europe is better than going it alone.
• The pandemic has changed so many lives. People have died earlier than they would otherwise have done, many more have been seriously long term, education has been disrupted, and businesses have struggled or gone under.

There have been positive things too.

• Neighbours shopped for others in lockdowns.
• In our area, almost everyone kept to the rules on mask wearing and social distancing, so we are well down on the infection table.
• The internet proved a godsend, with WhatsApp messaging, and Zoom, Facetime and other virtual meetings.

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Covid-19 What the UK Got Wrong

Lockdown and border closures
(BBC News Was the scientific evidence for lockdown flawed? 19 Nov. 2020.)

23 Jan. 2020: A woman unknowingly infected with Covid-19 flew to the UK from Wuhan and passed through the airport undetected. Eight days later she and a family member became the first confirmed UK cases, followed by many others who spread the virus in February and March when returning from China and from holidays in Italy, France and Spain. It is now thought that there were 1,500 UK cases during that period, so the UK was hit hard. Closing borders earlier could have reduced UK infections.

Modellers used information about the early cases held in the First Few Hundred (FF100) database to assess how the virus might spread, but FF100 was missing basic epidemiological information. Data was needed not only on where the virus was coming from, but also on who was worst affected.

 Mid-February. Evidence from China showed older people were especially at risk, so modellers advised that 'cocooning' would reduce deaths. Unfortunately models did not reflect how care homes actually work, or the serious risk from agency staff working in multiple homes.

Early March. Due to lack of accurate date, plans were still based on a fairly slow growing pandemic with a peak of cases in 12 to 14 weeks. One scientist thought official figures (913 cases) were wrong and called for an immediate lockdown; experts now estimate there were 75,000. Investigation focused on cases in intensive care units, as there be very many more who had a mild symptoms. The prediction was for c.100,000 new cases each day by mid-March, followed about a week later by 20,000 people each day needing hospital treatment. It was also realized that the NHS data  was out of date, in many cases up to a week old.

17 March. First restriction imposed - stopping non-essential contact with others, unnecessary travel, working from home and avoiding pubs, clubs, theatres and other social venues. It was thought that without this cases could double every five or six days. Data from Italy indicated that the virus was spreading at nearly twice the speed that had been thought - with the NHS potentially just days away from being swamped.

So should we have acted earlier? Modelling now suggests that if lockdown had been imposed a week earlier, we may have avoided around half the number of deaths. Relying only on modelling and using that alone to drive the response it turns out was not the right thing to do.

Test and Trace
(BBC News Coronavirus: inside test-and-trace - how the 'world-beater' went wrong. 20 Nov. 2020)

Just half of close contacts reported to England's Test and Trace are being reached in some areas. As attempts continue to get it back on track, it is still struggling with the legacy of decisions made at the outset.

NHS Test and Trace is not one whole service nor is it part of the NHS. It is a complex web of several programmes that have been bolted together quickly. Private firms play a key role, so some of the local expertise available in the NHS, universities and councils has been bypassed.

Private contractors overpromised what they could do (e.g. saying they could build 200 testing machines when they did not even have a prototype).

17 March. No-one from NHS labs was at a key government meeting with private firms (e.g. health-technology firms Randox and ThermoFisher) where it was decided to set up large, centralised labs outside any existing healthcare or research structures. This network of six mega-labs (Lighthouse labs) process the bulk of the tests across the UK. Testing sites were set up by financial and tech services company Deloitte. The contact centre is run by Sitel, and the 18,000 contact tracers are mostly employed by outsourcing company Serco - but does include c. 3,000 clinicians, some from the NHS. (This applies to England only, the rest of the UK has their own arrangements.) Contracts were awarded very quickly and many had no penalty clauses for poor performance.

Nov. 2020. England now has a large testing capacity, which can process more than 500,000 virus tests a day (up from 2,000 per day). But the system still struggles to get results quickly, since many samples were sent long distances for processing. If the approach had remained local by using existing networks of hospital, university and Public Health England, turn around would be much quicker.

Other companies were selling testing machines to NHS labs which did testing for hospitals - but the kits and chemicals needed for those machines were in short supply and being bought by the privately-owned Lighthouse labs.

The later move to more local contact tracing by councils was undermined by IT problems, leading to a reliance on spreadsheets and delays getting contact details.

Testing Targets

The government focused on hitting very high testing targets, but less so on who should get tests and why. People working in hospitals were not screened unless they had symptoms, despite evidence showing significant transmission there. However despite being 'effectively discouraged' to do so, some labs set up regular screening for healthcare staff. (E.g. The Univ. of Cambridge research lab partnered with nearby Addenbrooke's to offer this, and by the end of June had screened more than 10,000 hospital staff to detect asymptomatic carriers.)

Sept. 2020. Just as the second wave was starting, tests became near-impossible to access, due to people returning from holidays and children going back to school. The Lighthouse labs struggled as they were unable to forecast the sample numbers which varied wildly from day to day - so having enough staff to process 10,000 samples and only receiving 2,000 or having more than expected. As those involved in setting up the labs didn't always have experience with viruses, procedures needed constant tweaking, and there were issues with recruitment and training.

Tracing

Of the c. 18,000 contact tracers hired, only about 3,000 had a clinical background. While those who get the best results are good communicators, tracers were told to follow heavily scripted cues. With no room for discretion, call handlers had to try to make individual calls to every member of a household and go through the same forms. Unfortunately contact tracers often get abuse because of this. The government now says the system will be changed.

Performance is not at the right level. Advisors say 80% of those who test positive should be reached and close contact details obtained, and 80% of those contacts should be reached and asked to isolate. In some areas only half of contacts are reached. A change to greater local involvement was announced in August but funding was only announced in late October. 

And local schemes still face problems due to the centralised system. Delays getting cases passed down from the national team. Cases passed on are missing key contact information or are duplicates of cases already traced. Lack of access to NHS Test and Trace central IT system means councils are forced to record the information they collect on spreadsheets. Councils are only allowed to trace the infected case, so cannot deal with family members, even if they are on the door-step.

While money was allocated to find individuals, there was little thought on how to support people asked to isolate. The number isolating after a positive test or as a close contact is not routinely measured. Some have argued that the isolation period is too long - some other countries only require 7 days. Financial support for those isolating is limited to statutory sick pay; a one-off £500 payment for those on benefits is not available if you've been told to isolate via the app. The consequence is that people are less cooperative. 

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