Table 1.

List of mutation differences in HA gene between Southern Hemisphere vaccine strains and Myanmar 2015–2019 viruses.

Representative Strain	Clade		Amino Acid Mutations in Each Nucleotide Position
2015		19	21	69	130	140	144	154	158	160	175	176	185	241	280	327	342	395	466	495	505
A/Switzerland/9715293/2013 a	3C.3a	L	G	D	S	S	A	S	G	N	S	K	P	N	K	Q	R	G	K	G	D
2015 Myanmar viruses	3C.2a	I	R	N	T	R	T	A	R	S	Y	T	S	D	R	H	K	R	R	R	N
2016		49	112	137	158	160	174	176	187	210	258	422	500
A/Hong Kong/4801/2014 b	3C.2a	R	S	N	R	S	N	K	N	P	I	I	G
2016 Myanmar viruses	3C.2a and 3C.2a1	Q	N	K	G	G	H	T	K	L	M	V	E
2017		78	94	108	112	137	151	158	176	187	210	287	305	327	372	422	500
A/Hong Kong/4801/2014 b	3C.2a	E	G	K	S	N	T	R	K	N	P	D	P	H	Q	I	G
2017 Myanmar viruses	3C.2a1b	G	D	R	N	K	K	G	T	K	L	N	S	Q	L	V	E
2018		64	78	108	140	144	151	160	174	176	187	213	223	235	277	325	327	363	422	495	546
A/Singapore/INFIMH-16-0019/2016 c	3C.2a1	I	E	K	S	T	T	S	N	T	K	Q	K	S	R	V	H	V	V	E	A
2018 Myanmar viruses	3C.2a and 3C.2a1b	R	G	R	R	A	K	K	H	R	N	R	R	F	Q	I	Q	M	I	G	V
2019		16	49	78	99	108	110	112	137	144	147	151	153	154	158	187	205	209	277	327	363
A/Switzerland/8060/2017 d	3C.2a2	A	R	E	K	K	Y	S	N	T	K	T	S	A	K	N	K	F	Q	H	V
2019 Myanmar viruses	3C.2a1b	T	Q	G	E	R	N	N	K	A	T	K	F	S	G	K	R	S	R	Q	M
		422	500	517	538	545	546
		I	G	Q	I	V	A
		V	E	R	M	I	V

^a Vaccine strain for 2015, ^b vaccine strain for 2016 and 2017, ^c vaccine strain for 2018, and ^d vaccine strain for 2019. Amino acid substitutions in bold represent common mutations for all isolates in each season, whereas those in normal font represent additional sporadic mutations observed in some of the relevant season strains.