Covid-19 loves to stalk us if we’re together indoors

Little by little we’re finding out what coronavirus is like. We’re getting to know its face. We’re learning how it behaves. All the information we’re gathering will help us to deal with it and treat it and with the festive season upon us we need to be more careful than ever.

Coronavirus is an efficient spreader. This may be due in part because it binds strongly to a particular cell, the ACE2 receptor in the upper ­respiratory tract and conjunctiva of the eye, so it can infect the upper respiratory tract and airways easily.

Once bound to these cells, the proteins on its surface, spike proteins, gain easy entry into the body.

Most transmission occurs at close range such as 15 minutes face to face inside two metres.

Spread is especially efficient within households and through gatherings of family and friends.

The infection rate within a ­household can be as high as 35%.

Sleeping in the same room as or being the partner of an infected person increases the risk of infection, but if the infected person can be isolated the risk of infection is lower.

Eating in close proximity with an infected person is high risk, as is sharing food and taking part in group activities. The risk of infection substantially increases indoors compared to outside.

The virus bonds to the ACE2 ­receptors wherever they are in the body and causes symptoms there. So the intestine is hit with diarrhoea, the kidney with diminishing renal function, the heart with cardiovascular complications. The liver as well.

The peak of Covid-19 infection ­coincides with the time that ­symptoms appear so a person is most ­infectious just before or within the first five days of the illness.

This transmission, one to two days before symptoms appear, is likely to cause a serious spread of Covid-19.

When the virus starts to multiply in the lungs, symptoms such as fever, muscle pain, headache, cough and breathing difficulties appear.

The virus also attacks the lining of the nose with a loss of the sense of smell, loss of taste or a horrible taste in the mouth.

Some seriously ill patients may ­experience septic shock and multi-organ failure. The virus also causes blood to clot in small arteries along with small haemorrhages in the lungs.

We’ve become familiar with the words “cytokine storm” when the immune system overreacts to the virus and causes extensive tissue damage.

The body has an antibody response to a range of Covid-19 proteins but antibodies aren’t detectable in the first four days of illness. They develop over four weeks.

So make sensible decisions this Christmas and stick to the rules to ensure you (and your loved ones) have a healthy new year.