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10.  How common is smell and taste loss in
COVID-19?
 30 to 80% of people with COVID-19 report loss of smell,
known as anosmia, Most of the time taste also is affected
since smell and taste work together to create flavor.

11.  ”In 2020, a systematic review of 24 studies about smell and
taste dysfunction indicated that 40% of people lose their sense
of taste (dysgeusia) or smell (anosmia) during a COVID infection.
 A different multicenter study conducted in 2021 found that the
number may be as high as 74%.

13.  Can you just lose your sense of taste or smell?
 It's unlikely to lose the sense of smell without also perceiving
a loss or change in taste.

15.  “Since taste relies on olfaction,” taste loss may be present
because of smell loss.
 Smell and taste are intertwined in our brain, so when you lose
your sense of smell, you also lose your sense of taste.

16.  “The tongue can detect basic tastes like sweet, sour, savory
and bitter, but the nose detects flavor” .
 “So if you lose your sense of smell and eat a strawberry candy,
for example, you might know you’re eating something sweet,
but you might not know that it’s strawberry flavored.”

19. Does the loss of taste and smell
mean you had a mild,
moderate or severe case of
COVID-19?

20.  Based on retrospective data, for patients who lose their sense
of smell, It's seems to be more common in those with mild
COVID-19 than in moderate-to-severe cases.
 It is common for anosmia to be the first and only symptom.

24.  There is a range of data points available but up to 80% of
COVID-19 patients experience some sort of subjective
disturbance in their sense of smell.
 But, for long-term smell loss, that number is actually much
smaller.

26.  “One study used objective smell testing and found that only
15% of COVID-19 patients experience a loss of smell for
more than 60 days and less than 5% experienced it for
longer than six months.

28.  Quality of life can be substantially impacted by the loss of
taste and smell, with possible effects including depression,
loss of appetite, and safety risks from lack of awareness
of gas leaks, smoke or spoiled food.

30.  We smell by using the millions of nerve cells called olfactory
neurons that sit in the mucous membrane of our nose.
 Different groups of these neurons detect different types
of smells.

31.  While the precise cause of smell dysfunction is not entirely
understood, the mostly likely cause is damage to the cells
that support and assist the olfactory neurons, called
sustentacular cells.

32.  “Initially it was thought that it is a direct invasion of virus into
the olfactory cells or the neurons, but now, as we understand
the process more, it seems like this impacts the supporting
cells and not the olfactory neurons directly”.

33.  The scientists discovered it was the cells supporting the
olfactory neurons that contained the ACE2 receptor, which
the SARS-CoV-2 virus attaches to in order to infect cells.
 Further research revealed that the olfactory neurons lack
the ACE2 receptors.

35.  SARS-CoV-2 targets the ACE2 receptor found on the surface
of sustentacular cells – the cells that support the olfactory
nerves in the nose , but not on olfactory neurons.
 If the supporting cells are compromised,the olfactory nerves
are unable to function correctly.”

39. olfactory sensory neurons (OSNs)

40.  COVID-19-related anosmia may arise from a temporary loss of
function of supporting cells in the olfactory epithelium, which
indirectly causes changes to olfactory sensory neurons.
 Olfactory Sensory neurons can detect and transmit the sense
of smell to the brain.

41.  If SARS-CoV-2 virus infects the support cells, they no longer
provide nutrients and structural support to the olfactory
neurons, leaving them damaged and unable to transmit smells
from the nose to the brain.

42.  If patients clear their infections before the supporting cells
become too damaged, this might spare the neighboring
olfactory neurons any collateral damage.

43.  Sustentacular cells can regenerate from stem cells, which
may explain why smell recovers quickly in most cases and
as the helper cells recover, the sense of taste and smell
recover too.
 In most cases, SARS-CoV-2 infection is unlikely to permanently
damage olfactory neural circuits and lead to persistent anosmia.

45. How long does the loss of
taste and smell last?

46. After COVID, When Will
Sense of Smell Return?

47.  After having coronavirus (COVID-19), you may still have a loss
of, or change in, sense of smell or taste. It can take time for
your sense of smell or taste to recover.

48.  Most of the time, when you lose your sense of smell, it’s
because the virus has attacked the support cells.
 When these support cells regenerate (on average four to six
weeks later; for some it takes longer) your sense of smell will
return.”

49.  The path to recovery of taste and smell varies widely among
affected individuals.
 Most people will recover their sense of smell, although some
may experience an altered sense of smell from their previous
baseline.

50. How long it takes to smell again
 Early data shows that 95% or more of people fully recover
their sense of smell after COVID-19.
 What's more variable is how long it takes. The vast majority
of people recover their sense of smell in two or three weeks.
For a smaller percentage of patients, it may take months.

51.  Around 80 percent of patients will recover their sense of smell
within one to four weeks, and 95 percent will recover their
smell within six months.
 The prognosis for the approximately 5 percent of patients who
have not recovered their smell after six months is actively being
studied.

52.  For remaining 5 to 10% of people either their smell doesn’t come
back, it comes back reduced or comes back in a distorted way.
 The distorted sense of smell, known as parosmia, can present
with patients reporting that normally pleasant smells are now
very unpleasant, with odours they describe being like garbage,
burnt rubber or smoke.

53.  Nearly all people with COVID-19 who lost their sense of smell
gained it back.
 "Persistent COVID-19-related anosmia has an excellent prognosis
with nearly complete recovery at 1 year.

54.  Since the sense of smell usually diminishes due to age, the
recovery could take longer and be less than complete for older
adults.
 Those under 40 more likely than older adults to recover COVID-
related smell and taste loss.

56.  In most cases, smell dysfunction recovers quickly. However,
it can take months. In a minority of cases, recovery can be
incomplete with lasting impairment.
 While no proven treatment is available, olfactory training is
recommended.

59.  Olfactory training, while this “physical therapy for the nose”
may not work for everyone, it is the only proven form of
treatment we have.
 Another option for patients with anosmia is to try steroid
nasal sprays.

61.  Experts have argued that smell training is preferable to
steroids for people suffering from a lack of smell and taste
as a result of Covid.
 Topical corticosteroid sprays are often used in short-term
treatment, but they are unlikely to help outside of the
acute illness period.

67.  Recommend picking four scents, intense odors essential oils
(clove, eucalyptus, lemon, and rose) sniffing them twice a day,
spending around 20 seconds on each scent, over a period
of 12 weeks.
 These odors were originally chosen because they reflect distinct
categories of the “Fragrance Wheel.”
Olfactory training

69.  Starting with the first scent, take gentle whiffs of it for 20
seconds. While you’re smelling it, imagine what the smell
looks like, what it feels like.
 Recall a memory that involves this particular scent. “Memory
and smell are tightly connected in the brain” .

71. The goal of Olfactory training, is to rebuild the
connections between your brain and your nose.

72.  “Smell goes directly to the brain’s emotional center, including
the areas responsible for processing emotion and memory.
 That’s why, for example, when you smell chlorine, it may remind
you of swimming lessons. Olfactory training can teach the brain
to remake connections back to specific scents.

73.  Give your brain one minute to process that scent. When a
minute is up, take gentle whiffs of the next scent for 20
seconds. Let your brain process that scent for a minute.
Continue until you’ve smelled each of the four scents.

74.  In Olfactory training, Repetition is key. "You should spend
time on olfactory training every day, just like you would
exercise".
 Anywhere from 30% to 50% of patients who do olfactory
training see an improvement in their sense of smell after
12 weeks.

75.  Do olfactory training, twice a day, morning and night, for
three months.
 If your sense of smell hasn’t fully returned after three
months, find four new essential oils and repeat the exercise.

76.  “Time is very important for this exercise, as it takes time for
the olfactory nerves to recover, It’s like running a marathon.
You need to train slowly and persevere.”
 The earlier you start smell training, the more it may be able
to help.

77.  Your sense of smell will likely come back in stages. “Even if
it takes a while, the good news is that if you regain any hints
of smell, it’s just a matter of time until it fully returns.
 It takes time to recover. For some, it could take a year.

78.  The bad news is that not everyone will return to his or her
pre-COVID level of functioning. And, sadly, some of us might
never regain our sense of smell or taste at all.
 Since the sense of smell usually diminishes due to age, the
recovery could take longer and be less than complete for
older adults.