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What is a good antibody response range? What would a healthy young person expect to get?

Ask the Doctor Question:

See SARS COV 2 test below for my question. My husband is 74 and diagnosed with CLL/ SLL on his 64th birthday. He remains stable at 0/1 Stage and has not received any treatment. He was diagnosed with CLL, neuropathy, melanoma in situ, and hypothyroidism at the same time. The hypothyroidism is treated with levothyroxine and receives regular acupuncture for the neuropathy. He is also a Vietnam veteran exposed to agent orange. Otherwise, he is healthy as far as blood work goes and is not a diabetic. He has episodes of fatigue, is able to exercise, and eats healthy. Two years ago, he got influenza type A and yes, he had the high dose flu shot. It was a particularly bad case of influenza. He had two Moderna shots with the second given on 4/1/2021. On 6/21, the doctor tested his blood to see if he made any COVID antibodies after the vaccine:

SARS COV 2 AB (IGG) SPIKE, SEMI QN by Quest Diagnostics, Seattle

Results: H 5.54

Less than 1 negative

More than 1 positive

Other than disclaimers, there are no units of measurement and no range. The doctor’s note only says “positive.” While yes, I realize positive is good news, what is the range? What would a healthy young person expect to get?

Answer: The good news is that your husband had a response to the vaccine. The not so good news is that we don’t know what the values mean yet and what range equates to a protective level. The science just isn’t there yet.

We can tell you that if the Semi-quant value is <0.80, there was no response. If the Semi‑Quantitative Total Ab number is >0.80, there was a response to the vaccine.

It is important to take into consideration that the maximum value for the Spike antibody response can be upwards of 2,500. So, the 2,500 value is clearly greater than that of your husband. While we know that the greater the number equates to more antibodies, at this time we do not fully understand if a lower antibody value equates to a lesser level of protection should you become infected with COVID. It’s true that some immunity is better than no immunity at all, but we can all guess that a low count is unfortunately not ideal.

CLL Society is still urging everyone with CLL, regardless of vaccine and/or antibody status, to continue wearing a tightly fitted face mask over the nose and mouth in all situations that involve leaving the home. Also, please continue to adhere closely to social distancing, and keep up with diligent hand hygiene efforts, especially now that the general population is unmasked, and the Delta variant is spreading. We are beginning to hear anecdotal reports of healthy fully vaccinated people who are testing positive and are symptomatic now more than ever. So, it’s just extremely important to remain vigilant.

The true interpretation of the Spike antibody test will become known over time as we learn the association between these results and how it correlates to the chance of still getting infected with COVID in the near future. There are currently many researchers with expertise in blood cancer who are looking at this very subject and performing studies. We should be hearing more about this subject in the coming months.